Electrophoretic particle, method of manufacturing electrophoretic particle, electrophoresis dispersion liquid, electrophoresis sheet, electrophoresis device, and electronic apparatus

ABSTRACT

An electrophoretic particle includes a base particle (particle), a first compound, a second compound, and a third compound bonded to the base particle. The first compound is a polymer having a dispersion portion derived from a first monomer, and a bonding portion derived from a second monomer, and is connected to the base particle at the bonding portion. The second compound includes a non-polar group and a second functional group and is connected to the base particle at the second functional group. The third compound includes a charging group and a second functional group and is connected to the base particle at the second functional group.

BACKGROUND

1. Technical Field

The present invention relates to an electrophoretic particle, a methodof manufacturing an electrophoretic particle, an electrophoresisdispersion liquid, an electrophoresis sheet, an electrophoresis device,and an electronic apparatus.

2. Related Art

In general, it is known that the fine particles are moved (migrate) inthe liquid due to Coulomb force when an electrical field is operated ina dispersion system in which fine particles are dispersed in a liquid.This phenomenon is known as electrophoresis, and in recent years,electrophoresis display devices in which desired information (images) isdisplayed using electrophoresis have garnered attention as new displaydevices.

The electrophoresis display device has display memory properties in astate in which application of a voltage is stopped and wide viewingangle properties, and is capable of high contrast display with low powerconsumption.

Since electrophoresis display devices are non-light emitting displaydevices, electrophoresis display devices are better for the eyescompared to a light-emitting display device such as a cathode ray tube.

Such an electrophoresis display device provided with a dispersion inwhich the electrophoretic particles are dispersed in a solvent as anelectrophoresis dispersion liquid arranged between a pair of substrateshaving electrodes is known.

In an electrophoresis dispersion liquid with this configuration,electrophoretic particles including particles with positivechargeability and particles with negative chargeability are used, and,accordingly, it is possible for desired information (images) to bedisplayed by applying a voltage between the pair of substrates(electrodes).

Particles provided with a coating layer 503 in which a polymer 533 isconnected to a base material particle 502 are generally used as theelectrophoretic particles 501 (refer to FIG. 10), and theelectrophoretic particles 501 can be dispersed and charged in theelectrophoresis dispersion liquid by using a configuration provided withsuch a coating layer 503 (polymer 533).

The electrophoretic particles with this configuration are manufacturedas follows, for example, using atom transfer radical polymerizationreaction (ATRP).

That is, after base material particles 502 are prepared, and a silanecoupling agent 531 having a polymerization initiation group is bonded tothe surface of the base material particles 502, electrophoreticparticles 501 are manufactured through imparting characteristics such asdispersibility by providing a polymer 533 while forming a polymerizationportion 532 at which a monomer is polymerized by living radicalpolymerization with the polymerization initiation group as an origin(for example, refer to JP-A-2013-156381).

Incidentally, regarding whether the electrophoretic particles 501 havepositive chargeability or negative chargeability in the electrophoreticparticles 501 with this configuration, because the base materialparticles 502 themselves have inherent chargeability it is possible fora desired chargeability to be imparted on the electrophoretic particles501 by selecting, as appropriate, the type of base material particle502.

However, in the electrophoresis display device, although it is necessaryto control the charging amount of the electrophoretic particles 501 inorder to set the migration speed of the electrophoretic particles 501 toa suitable speed, it is difficult to control the charging amount of theelectrophoretic particles 501 to a suitable range by simply providingthe polymer 533 on the base material particle 502.

SUMMARY

An advantage of some aspects of the invention is to provideelectrophoretic particles which include a uniform dispersion capacity inthe electrophoresis dispersion liquid and for which the charging amountis set to a suitable range, a method of manufacturing an electrophoreticparticle that is able to manufacture the electrophoretic particle, and ahigh reliability electrophoresis dispersion liquid, electrophoresissheet, electrophoresis device, and electronic apparatus in which theelectrophoretic particles are used.

This advantage is achieved by the invention described below.

According to an aspect of the invention, there is provided anelectrophoretic particle including: a particle including a firstfunctional group on a surface; and a first compound, a second compound,and a third compound bonded to the particle, in which the first compoundis a block copolymer that includes a dispersion portion derived from afirst monomer including a site that contributes to dispersibility in adispersion medium, and a bonding portion derived from a second monomerincluding a second functional group having reactivity with the firstfunctional group, and is connected to the particle by reacting the firstfunctional group and the second functional group in the bonding portion,the second compound has a lower molecular weight than the firstcompound, includes a non-polar group and the second functional group,and is connected to the particle by the second functional group reactingwith the first functional group, and the third compound has a lowermolecular weight than the first compound, includes a charging group andthe second functional group, and is connected to the particle by thesecond functional group reacting with the first functional group.

Accordingly, electrophoretic particle which is provided with a uniformdispersion capacity in the electrophoresis dispersion liquid and forwhich the charging amount is set to a suitable range can be formed.

In the electrophoretic particles, it is preferable that the secondcompound be a silane coupling agent that includes the non-polar groupand the second functional group.

Accordingly, the second compound can be reliably interposed in a regionbetween the first compounds and the third compounds connected to theparticles. As a result, the dispersibility of the electrophoreticparticles in the electrophoresis dispersion liquid can be made superior.

In the electrophoretic particle, it is preferable that the secondcompound be a block copolymer that includes a non-polar portion derivedfrom a third monomer including the non-polar group, and the bondingportion derived from the second monomer including the second functionalgroup.

Accordingly, the second compound can be reliably interposed in a regionbetween the first compounds and the third compounds connected to theparticles. As a result, the dispersibility of the electrophoreticparticles in the electrophoresis dispersion liquid can be made superior.

In the electrophoretic particle, it is preferable that the non-polargroup be a hydrocarbon group.

Because these groups exhibit superior non-polarity, aggregation betweenthe electrophoretic particles can be more precisely suppressed orprevented.

In the electrophoretic particle, it is preferable that the molecularweight of the second compound be 100 or more to 1,000 or less.

Accordingly, the steric hindrance of the second compound is reduced andthe second compound can be more reliably interposed in a region betweenthe first compounds and the third compounds connected to the particles.As a result, the dispersibility of the electrophoretic particles in theelectrophoresis dispersion liquid can be made superior.

In the electrophoretic particle, it is preferable that the thirdcompound be a silane coupling agent that includes the charging group andthe second functional group.

Accordingly, the third compound can be reliably interposed in a regionbetween the first compounds and the second compounds connected to theparticles. As a result, chargeability can be reliably imparted to theelectrophoretic particles in the electrophoresis dispersion liquid.

In the electrophoretic particle, it is preferable that the thirdcompound be a block copolymer that includes a charging portion derivedfrom the third monomer including the charging group, and the bondingportion derived from the second monomer including the second functionalgroup.

Accordingly, the third compound can be reliably interposed in a regionbetween the first compounds and the second compounds connected to theparticles. As a result, it is possible to reliably impart chargeabilityto the electrophoretic particles in the electrophoresis dispersionliquid.

In the electrophoretic particle, it is preferable that the charginggroup include at least one of a polarization group and an ionic group.

Among these, the third compound can reliably provide positive ornegative chargeability.

In the electrophoretic particle, it is preferable that the molecularweight of the third compound be 100 or more to 1,000 or less.

Accordingly, the steric hindrance of the third compound is reduced andthe third compound can be more reliably interposed in a region betweenthe first compounds and the second compounds connected to the particles.As a result, chargeability can be reliably imparted to theelectrophoretic particles in the electrophoresis dispersion liquid.

In the electrophoretic particle, it is preferable that, in the firstcompound, the bonding portion be formed by 1 or more to 10 or less unitsderived from the second monomer.

Accordingly, a chemical bond can be formed between the bonding portionand the particle, and the block copolymer can be reliably connected tothe particle.

In the electrophoretic particle, it is preferable that, in the firstcompound, the first monomer be a silicone macromonomer represented bythe following general formula (I).

[in the formula, R¹ is a hydrogen atom or a methyl group, R² is ahydrogen atom or an alkyl group having 1 to 4 carbon atoms, R³ is astructure including one type from an alkyl group having 1 to 6 carbonatoms and an ether group of ethylene oxide or propylene oxide, and n isan integer of 0 or more]

Accordingly, when using a medium with silicone oil as a main componentas the dispersion medium included in the electrophoresis dispersionliquid, the electrophoretic particles that include the dispersionportion obtained by polymerizing the first monomer can have superiordispersibility and be dispersed in the dispersion medium because thefirst monomer exhibits superior affinity with respect to the dispersionmedium.

In the electrophoretic particle, it is preferable that the weightaverage molecular weight of the dispersion portion be 10,000 or more to100,000 or less.

Accordingly, the electrophoretic particles provided with the dispersionportion can have superior dispersibility and be dispersed in thedispersion medium.

In the electrophoretic particle, it is preferable that, when the weightaverage molecular weight of the dispersion portion is A and themolecular weight of the second compound is B, A/B be 10 or more to 1,000or less.

Accordingly, the steric hindrance of the second compound is reduced andthe second compound can be more reliably interposed in a region betweenthe first compounds connected to the particles. As a result, thedispersibility of the electrophoretic particles in the electrophoresisdispersion liquid can be made superior.

According to another aspect of the invention, there is provided a methodof manufacturing an electrophoretic particle of the above aspects of theinvention, the method including: connecting the third compound to theparticle by reacting the first functional group included in the surfaceof the particle and the second functional group included in the thirdcompound; connecting the first compound to the particle at the bondingportion by reacting the first functional group included in the surfaceof the particle and the second functional group included in the firstcompound; and connecting the second compound to the particle by reactingthe first functional group included in the surface of the particle andthe second functional group included in the second compound.

Accordingly, an electrophoretic particle which is provided with auniform dispersion capacity in the electrophoresis dispersion liquid andfor which the charging amount is set to a suitable range can bemanufactured.

According to another still aspect of the invention, there is provided anelectrophoresis dispersion liquid including: the electrophoreticparticles of the above aspects of the invention; and a dispersionmedium.

Accordingly, an electrophoresis dispersion liquid provided withelectrophoretic particles which include a uniform dispersion capacity,and for which the charging amount is set to a suitable range can beprovided.

In the electrophoresis dispersion liquid, it is preferable that thedispersion medium be silicone oil.

Silicone oil has excellent weather resistance because of not havingunsaturated bonds, and has the further advantage of high safety.

According to still another aspect of the invention, there is provided anelectrophoresis sheet including: a substrate; and a structure that isprovided on the substrate, and that accommodates the electrophoresisdispersion liquid of the above aspects of the invention.

Accordingly, a high performance and high reliability electrophoresissheet is obtained.

According to still another aspect of the invention, there is provided anelectrophoresis device including the electrophoresis sheet of the aboveaspects of the invention.

Accordingly, a high performance and high reliability electrophoresisdevice is obtained.

According to still another aspect of the invention, there is provided anelectronic apparatus including the electrophoresis device of the aboveaspects of the invention.

Accordingly, a high performance and high reliability electronicapparatus is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a longitudinal cross-sectional view illustrating a firstembodiment of an electrophoretic particle of the invention.

FIG. 2 is a schematic view of a first compound, a second compound, and athird compound included in a first embodiment of the electrophoreticparticles of the invention.

FIG. 3 is a schematic view of a first compound, a second compound, and athird compound included in a second embodiment of the electrophoreticparticles of the invention.

FIG. 4 is a view schematically illustrating a longitudinal cross-sectionof an embodiment of an electrophoresis display device.

FIG. 5 is a schematic view illustrating an operation principle of theelectrophoresis display device shown in FIG. 4.

FIG. 6 is a schematic view illustrating an operation principle of theelectrophoresis display device shown in FIG. 4.

FIG. 7 is a perspective view illustrating an embodiment of a case wherean electronic apparatus of the invention is applied to an electronicpaper.

FIG. 8 is a view illustrating an embodiment of a case where theelectronic apparatus of the invention is applied to a display.

FIG. 9 is a view illustrating an embodiment of a case where theelectronic apparatus of the invention is applied to a display.

FIG. 10 is a view schematically illustrating a longitudinalcross-section of a structure in an electrophoretic particle of therelated art.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Below, the electrophoretic particles, the method of manufacturing theelectrophoretic particles, the electrophoresis dispersion liquid, theelectrophoresis sheet, the electrophoresis device, and the electronicapparatus of the invention will be described in detail based onfavorable embodiments illustrated in the attached drawings.

Electrophoretic Particle First Embodiment

First, a first embodiment of the electrophoretic particles of theinvention will be described.

FIG. 1 is a longitudinal cross-sectional view illustrating the firstembodiment of an electrophoretic particle of the invention, and FIG. 2is a schematic view of first, second, and third compounds included inthe first embodiment of the electrophoretic particles of the invention.

The electrophoretic particle 1 includes a base particle (particle) 2 anda coating layer 3 provided on the surface of the base particle 2.

At least one type of pigment particle, resin particle or compositeparticle thereof is favorably used as the base particle 2. Theseparticles are easily manufactured.

Examples of the pigment that forms the pigment particles include blackpigments such as aniline black, carbon black, and titanium black, whitepigments such as titanium dioxide, titanium trioxide, barium sulfate,zinc sulfide, and silicon dioxide, azo pigments such as monoazo, diazo,and polyazo, yellow pigments such as isoindolinone, chrome yellow,cadmium yellow, titanium yellow, and antimony, red pigments such asmonoazo, diazo, and polyazo, red pigments such as quinacridone red, andchrome vermillion, blue pigments such as phthalocyanine blue,indanthrene blue, prussian blue, ultramarine, and cobalt blue, and greenpigments such as phthalocyanine green, and it is possible to use onetype or a combination of two or more types thereof.

Examples of the resin material that forms the resin particles includeacrylic resins, urethane resins, urea resins, epoxy resins, polystyrene,and polyester, and it is possible to use one type or a combination oftwo or more types thereof.

Examples of the composite particles include particles subjected to acoating process by coating the surface of a pigment particle with aresin material, particles subjected to a coating process by coating thesurface of a resin particle with a pigment, and particles configured bya mixture in which a pigment and a resin material are mixed as anappropriate compositional ratio.

It is possible to set the color of the electrophoretic particles 1 to adesired color by selecting, as appropriate, the type of pigmentparticles, resin particles and composite particles used as the baseparticle 2.

It is necessary that the base particles 2 include (exposed) a firstfunctional group that is able to bond (react) to a bonding portion 31 ofthe first compound 39, described later, and the second functional groupincluded in the second compound 37 and the third compound 35 in thesurface thereof. However, because there are cases where a functionalgroup is not included according to the type of pigment particles, resinparticles and composite particles, in this case, the particles may besubjected in advance to a functional group introduction process such asacid treatment, basic treatment, UV treatment, ozone treatment, andplasma treatment, and the first functional group introduced to thesurface of the base particles 2.

The combination of the first functional group included in the surface ofthe base particle 2, the bonding portion 31 of the first compound 39,and the second functional group included in the second compound 37 andthe third compound 35, is not particularly limited as long as they canreact with one another to be connected, and examples thereof include acombination of an isocyanate group and a hydroxyl group or an aminogroup, a combination of an epoxy group, a glycidyl group or an oxetanegroup and a carboxyl group, an amino group, a thiol group, a hydroxylgroup, or an imidazole group, a combination of an amino group and ahalogen group such as Cl, Br, and I, and a combination of an alkoxysilylgroup and a hydroxyl group or an alkoxysilyl group. Among these, acombination where the first functional group is a hydroxyl group and thesecond functional group is an alkoxysilyl group is preferable.

Since it is possible for the base particles 2 in which these arecombined, the monomer M2, the second compound 37, and the third compound35 to each be comparatively easily prepared, and possible for themonomer M2 (block copolymer, described later), the second compound 37,and the third compound 35 to be strongly connected to the surface of thebase particle 2, these are preferably used.

Here, an example of a combination in which the first functional groupincluded in the surface of the base particles 2 is a hydroxyl group andthe second functional group included in the monomer M2, the secondcompound 37 and the third compound 35 is an alkoxysilyl group will bedescribed.

Substantially the entire surface of the base particle 2 is covered bythe coating layer 3.

The coating layer 3 has a configuration which includes a plurality ofthe first compound 39, the second compound 37 with a lower molecularweight than the first compound 39, and the third compound 35 with alower molecular weight than the first compound 39 (refer to FIG. 2).

It should be noted that although the second compound 37 has a non-polargroup and a second functional group which has reactivity with the firstfunctional group included in the base particle 2, in the embodiment, thesecond compound 37 is a silane coupling agent having a non-polar groupand a second functional group, and further, although the third compound35 has a charging group and a second functional group having reactivitywith the first functional group included in the base particle 2, in theembodiment, a case where the third compound 35 is a silane couplingagent having a charging group and a second functional group will bedescribed.

The first compound 39 is a block copolymer having a dispersion portion32 derived from the first monomer M1 (below, also referred to simply as“monomer M1”) having a site (group) that contributes dispersibility inthe dispersion medium and a bonding portion 31 derived from a secondmonomer M2 (below, also simply referred to “monomer M2”) that includesthe second functional group having reactivity with the first functionalgroup. The first compound is connected to the base particles 2 byreacting the first functional group and the second functional group atthe bonding portion 31.

By the first compound 39 having this configuration, dispersibility isimparted to the dispersion portion 32 configured by a unit (below, alsoreferred to as a dispersion unit) derived from the monomer M1, the firstcompound is connected to the base particles 2 by the bonding portion 31configured by a unit (below, also referred to as a bonding unit) derivedfrom the monomer M2. Therefore, the electrophoretic particles 1including the first compound 39 with this configuration are able toexhibit a uniform dispersion capacity in the electrophoresis dispersionliquid. That is, the first compound 39 is connected to the surface ofthe base particle 2 in order for a uniform dispersion capacity to beexhibited by the electrophoretic particles 1 in the electrophoresisdispersion liquid.

The dispersion portion 32 at which the first monomer M1 is polymerizedand the bonding portion 31 at which the second monomer M2 is polymerizedare connected with the first compound 39. In the first compound 39 withthis configuration, the dispersion portion 32 includes a plurality ofdispersion units which are formed by polymerizing the monomer M1 and arederived from the monomer M1, and further, the bonding portion 31includes a plurality of bonding units which are formed by polymerizingthe monomer M2, and are derived from the monomer M2. The base particles2 and the first compound 39 are chemically bonded at the bonding portion31 included in the first compound 39 via a bonding group formed byreacting the first functional group and the second functional group.

Below, the dispersion portion 32 and the bonding portion 31 thatconfigure the first compound 39 will be described.

The dispersion portion 32 is provided in the surface of the baseparticles 2 in the coating layer 3 in order to impart dispersibility tothe electrophoretic particles 1 in the electrophoresis dispersionliquid, described later.

The dispersion portion 32 is connected to a plurality of dispersionunits which are formed by polymerizing a plurality of the monomer M1having a site that is a side-chain that contributes to dispersibility inthe dispersion medium after polymerization in the electrophoresisdispersion liquid, and is derived from the monomer M1.

The monomer M1 includes one polymerizable group that is able to bepolymerized by live radical polymerization (radical polymerization), andafter further polymerization is a pendant-type monofunctional monomerthat includes a site that is a non-ionic side-chain.

By using a monomer M1 that includes a non-ionic side-chain, thedispersion portion 32 formed by live radical polymerization exhibitssuperior affinity to the dispersion medium included in theelectrophoresis dispersion liquid, described later. Therefore, theelectrophoretic particles 1 that include the dispersion portion 32 havesuperior dispersibility and are dispersed in the electrophoresisdispersion liquid without being aggregated.

Examples of the one polymerizable group included in the monomer M1include those that include a carbon-carbon double bond, such as a vinylgroup, a styryl group, and a (meth)acryloyl group.

Examples of the monomer M1 include vinyl monomers, vinyl ester monomers,vinyl amide monomers, (meth)acrylic monomers, (meth)acrylic estermonomers, (meth)acrylic amide monomers and styryl monomers, and morespecifically, acrylic monomers such as 1-hexane, 1-heptane, 1-octane,methyl (meth) acrylate, ethyl (meth)acrylate, propyl (meth)acrylate,stearyl (meth)acrylate, lauryl (meth)acrylate, decyl (meth)acrylate,isooctyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl(meth)acrylate, and pentafluoro (meth)acrylate, and siliconemacromonomers represented by the following general formula (I) andstyrene monomers such as such as styrene, 2-methyl styrene, 3-methylstyrene, 4-methyl styrene, 2-ethyl styrene, 3-ethyl styrene, 4-ethylstyrene, 2-propyl styrene, 3-propyl styrene, 4-propyl styrene,2-isopropyl styrene, 3-isopropyl styrene, 4-isopropyl styrene, and4-tert-butyl styrene, and it is possible to use one type or acombination of two or more types thereof.

[in the formula, R¹ is a hydrogen atom or a methyl group, R² is ahydrogen atom or an alkyl group having 1 to 4 carbon atoms, R³ is astructure including one type from an alkyl group having 1 to 6 carbonatoms and an ether group of ethylene oxide or propylene oxide, and n isan integer of 0 or more]

Among these, it is preferable that the monomer M1 be a siliconemacromonomer represented by the above general formula (I). Thedispersion portion that is able to polymerize the monomer M1 exhibitssuperior dispersibility with respect to the non-polar dispersion medium.That is, although a medium having silicone oil as the main component isused as the dispersion medium included in the electrophoresis dispersionliquid, described later, even in a case of using a hydrocarbon-basedsolvent as in the silicone oil, superior affinity to the dispersionmedium. Therefore, it is possible for the electrophoretic particles 1provided with the dispersion portion 32 obtained by polymerizing themonomer M1 to have superior dispersibility and be dispersed in thedispersion medium.

In a case of using the silicone macromonomer represented by the abovegeneral formula (I) as the monomer M1, it is preferable that the weightaverage molecular weight thereof be approximately 1,000 or more to60,000 or less, approximately 3,000 or more to 30,000 or less is morepreferable, and approximately 5,000 or more to 20,000 or less is stillmore preferable. Accordingly, it is possible for the electrophoreticparticles 1 provided with the dispersion portion 32 obtained bypolymerizing the monomer M1 to have superior dispersibility and bedispersed in the dispersion medium.

It is preferable that the weight average molecular weight of thedispersion portion 32 be 10,000 or more to 100,000 or less, and 10,000or more to 60,000 or less is more preferable. In particular, in a caseof using a silicone macromonomer such as represented by the generalformula (I) as the or a case of using a hydrocarbon-based monomer as themonomer M1, it is preferable that the weight average molecular weight ofthe dispersion portion 32 is 8,000 or more to 50,000 or less and 10,000or more to 35,000 or less is more preferable. Accordingly, it ispossible for the dispersibility of the electrophoretic particles 1 inthe electrophoresis dispersion liquid to be made superior.

In one polymer, it is preferable that the number of dispersion unitsincluded in the dispersion portion 32 be 1 or more to 20 or less, and 2or more to 10 or less is more preferable. Accordingly, it is possiblefor the dispersibility of the electrophoretic particles 1 in theelectrophoresis dispersion liquid to more reliably imparted.

It is preferable that the molecular weight distribution of thedispersion portion 32 be 1.2 or less, 1.1 or less is more preferable,and 1.05 or less is still more preferable.

The molecular weight distribution of the dispersion portion 32represents the ratio (Mw/Mn) between the number average molecular weight(Mn) of the dispersion portion 32 and the weight average molecularweight (Mw) of the dispersion portion 32, it can be said that thedispersion portions 32 exposed in the plurality of electrophoreticparticles 1 have a substantially uniform length by the molecular weightdistribution of the dispersion portion 32 being within the above ranges.Therefore, each electrophoretic particle 1 exhibits a uniform dispersioncapability in the electrophoresis dispersion liquid. It is possible tomeasure number average molecular weight (Mn) and the weight averagemolecular weight (Mw) as a polystyrene conversion molecular weight usinga gel permeation chromatography (GPC) method.

Furthermore, it is preferable for the dispersion portion 32 to have amolecular weight of the dispersion unit of the base end portion sideconnected to the bonding portion 31 lower than the molecular weight ofthe dispersion unit on the tip end side. More specifically, it ispreferable that the molecular weight of the side chain included in themonomer M1 that is a precursor of the dispersion unit positioned on thebase end portion side is lower than the molecular weight of theside-chain included in the monomer M1 that is a precursor of thedispersion unit positioned on the tip end side. Accordingly, it ispossible to make the dispersibility of the electrophoretic particles 1in the electrophoresis dispersion liquid superior and for the dispersionportion 32 to be highly densely bonded to the surface of the baseparticles 2.

It should be noted that changes in the molecular weight of theside-chain may continuously increase from the based end side towards theleading end side, or may increase step-wise from the base end sidetoward the leading end side.

The bonding portion 31 is bonded to the surface of the base particle 2in the coating layer 3 included in the electrophoretic particles 1, andin so doing the first compound 39 is connected to the base particles 1.

The bonding portion 31, in the invention, can form a common bond by thebase particle 2 and the hydroxyl group included in the surface thereofbeing bonded, and is formed by polymerizing a plurality of the secondmonomer M2 including the functional group, and a plurality of bondingunits (constituent unit) derived from the monomer M2 are connected.

In this way, by using the first compound 39 including a plurality ofbonding portions 31 each including the functional group, it is possiblefor the dispersibility of the electrophoretic particles 1 to be madesuperior. That is, the first compound 39 not only includes a pluralityof functional groups, but the plurality of functional groups are presentconcentrated at the bonding portion 31. Furthermore, because the bondingportion 31 is connected to a plurality of bonding units, the sitecapable of reacting with the base particles 2 is large compared to acase where there is only one bonding unit. Therefore, it is possible forthe first compound 39 to be reliably bonded to the surface of the baseparticle 2 at the bonding portion 31 formed by polymerizing theplurality of monomers M2.

In the embodiment, the hydroxyl group is included in the surface of thebase particle 2, and the functional group included in the monomer M2becomes an alkoxysilyl group, as described above. By making thecombination of such a hydroxyl group and an alkoxysilyl group, since thereaction between the groups indicates superior reactivity, it ispossible for the bond to the surface of the base particle 2 to be morereliably formed at the bonding portion 31.

The monomer M2 includes one alkoxysilyl group represented by thefollowing general formula (II) as the functional group, and furtherincludes one polymerizable group so as to be able to be polymerized bylive radical polymerization.

[in the formula, each R independently represents an alkyl group having 1to 4 carbon atoms, and n represents an integer of 1 to 3.]

By using such a configuration as the monomer M2, it is possible tocreate the bonding portion 31 at which the monomer M2 is polymerized bylive radical polymerization, and further the bonding portion 31 formedby live radical polymerization exhibits superior reactivity to thehydroxyl group positioned in the surface of the base particles 2.

Examples of the one polymerizable group included in the monomer M2include those that include a carbon-carbon double bond, such as a vinylgroup, a styryl group, and a (meth)acryloyl group, similarly to themonomer M1.

Examples of the monomer M2 include vinyl monomers including onealkoxysilyl group represented by the above general formula (II), vinylester monomers, vinyl amide monomers, (meth)acrylic monomers, (meth)acrylic ester monomers, (meth) acrylic amide monomers, and styrylmonomers, and more specifically include silane-based monomers containingsilicon atoms such as 3-(meth) acryloxypropyltriethoxy(methoxy) silane,vinyl triethoxy (methoxy) silane, 4-vinyl butyl triethoxy (methoxy)silane, 8-vinyl octyltriethoxy (methoxy) silane, 10-methacryloyloxydecyltriethoxy (methoxy) silane and 10-acryloyloxydecyl triethoxysilane(methoxy) silane, and it is possible to use one type or a combination oftwo or more types thereof.

In one polymer, it is preferable that the number of bonding unitsincluded in the bonding portion 31 be 1 or more to 10 or less, 2 or moreto 10 or less is more preferable, and 3 or more to 6 or less is stillmore preferable. Because the bonding portion 31 has a low affinity tothe dispersion medium compared to the dispersion portion 32 when theupper limit value is exceeded, there is concern of the dispersibility ofthe electrophoretic particles 1 being lowered and of the bondingportions 31 locally bonding with each other according to the type ofmonomer M2. When lower than the lower limit value, it is difficult forbonding with the base particles 2 to proceed sufficiently according tothe type of monomer M2, and there is concern of the dispersibility ofthe electrophoretic particles 1 being lowered caused by this difficulty.

It is possible for the number of bonding units included in the bondingportion 31 to be obtained by analysis using a general-purpose analyzer,such as NMR spectrum, IR spectrum, element analysis, gel permeationchromatography (GPC) or the like. Because the bonding portion 31 and thedispersion portion 32 are macromolecular polymers in the first compound39, both have a molecular weight distribution. Accordingly, although theresults of the analysis as outlined above are not limited tocorresponding to all of the first compound 39, it is possible for thereactivity between the first compound 39 and the base particles 2 andthe dispersibility of the electrophoretic particles 1 to both beachieved as long as the number of bonding units obtained with at leastthe above methods is 1 to 8.

The first compound 39 is a diblock copolymer in which bonding portion 31and the dispersion portion 32 are each separately provided. Therefore,because it is possible for the bondability to the base particles 2 andthe dispersibility of the electrophoretic particles 1 to each beindependently imparted on the first compound 39, the electrophoreticparticles 1 exhibit superior dispersibility.

The first compound 39 is obtained by a manufacturing method which isdescribed later. When reversible addition-fragmentation chain-transferpolymerization (RAFT), described later, is used, it is possible toobtain a comparatively uniform polymer. Accordingly, if polymerizationis performed by adding 1 to 8 mol equivalent of the monomer M2 withrespect to the chain transfer agent, it is possible for the number ofbonding units in the bonding portion 31 to be set to the above range.Accordingly, it is possible for the effects due to the electrophoreticparticles 1 having a configuration including the first compound 39 to bereliably exhibited, the electrophoretic particles 1 have superiordispersibility in the electrophoresis dispersion liquid.

It is preferable for the addition amount of the first compound 39 in theelectrophoretic particles 1 to the base particles 2 to be 1.0 wt % ormore to 6.0 wt % or less, and 2.0 wt % or more to 3.0 wt % or less ismore preferable. Accordingly, it is possible for the dispersibility ofthe electrophoretic particles 1 in the electrophoresis dispersion liquidto be made superior.

As described above, in the embodiment, the second compound 37 is asilane coupling agent that includes a non-polar group and a secondfunctional group.

The second compound 37 has a lower molecular weight than the firstcompound 39, and is connected to the base particle 2 at the secondfunctional group by reacting the first functional group and the secondfunctional group.

The second compound 37 includes a non-polar group. Accordingly, it ispossible to accurately suppress or prevent aggregation of theelectrophoretic particles 1 by the repulsive force between theelectrophoretic particles 1 arising due to each electrophoretic particle1 being provided with the second compound 37, without exerting anadverse influence on the dispersibility and the charging properties(charging amount) of the electrophoretic particles 1. For theaggregation between electrophoretic particles 1, it is possible to moreaccurately suppress aggregation between white particles 95 a and coloredparticles 95 b having reverse charges by the electrophoretic particles 1being applied to white particles 95 a having negative chargeability(negative charge) and colored particles 95 b having positivechargeability (positive charge) as in the electrophoresis display device920, described later. That is, the second compound 37 is connected tothe surface of the base particle 2 in the electrophoretic particle 1 inorder for aggregation between the electrophoretic particles 1 in theelectrophoresis dispersion liquid.

Below, each portion (non-polar group and second functional group) in thesilane coupling agent having a non-polar group and a second functionalgroup that is the second compound 37 in the embodiment will bedescribed.

The non-polar group is provided in the surface of the base particles 2in the coating layer 3 in order to suppress or prevent aggregationbetween electrophoretic particles 1 in the electrophoresis dispersionliquid, described later.

The non-polar group is not particularly limited as long as it showsnon-polarity, and examples thereof include hydrocarbon groups. Becausehydrocarbon groups exhibit superior non-polarity, it is possible to moreprecisely suppress or prevent aggregation between the electrophoreticparticles 1.

Examples of the non-polar group include alkyl groups, aryl groups,cycloalkyl groups, phenyl groups, alkenyl groups, aralkyl groups,cycloalkenyl groups, alkynyl groups, aryl ether groups, silyl groups,siloxanyl groups, and alkoxy groups, and, although it is possible to useone type or a combination of two or more types thereof, among these, analkyl group that is one type of hydrocarbon group is particularlypreferable. Because the non-polar group (hydrocarbon group) has astructure that is particularly difficult to charge, it is possible forthe effects to be more remarkably exhibited.

The hydrocarbon group preferably contains 1 to 20 carbon atoms, and morepreferably 1 to 10 carbon atoms. In so doing, it is possible for thesecond compound 37 to be more reliably connected to the region betweenthe first compounds 39 connected to the base particles 2 whileexhibiting a function as a non-polar group.

Although the non-polar group may form any of a straight chain shape, abranched shape, or a ring shape, a straight chain shape is preferable.Accordingly, the steric hindrance of the non-polar group is reduced andthe second compound 37 can be reliably interposed in a region betweenthe first compounds 39 connected to the base particles 2.

In the embodiment, as described above, the second functional group, isan alkoxysilyl group, and the first functional group included in thebase particles 2 is a hydroxyl group.

By making the combination of such a hydroxyl group and an alkoxysilylgroup, since the reaction between the groups indicates superiorreactivity, it is possible for the bond of the second compound 37 to thesurface of the base particle 2 to be more reliably formed at the secondfunctional group.

Examples of the second compound 37 that includes the second functionalgroup include silane coupling agents represented by the followinggeneral formula (III) when the non-polar group is D.

[in the formula, D represents a non-polar group, each R independentlyrepresents an alkyl group having 1 to 4 carbon atoms, and n representsan integer of 1 to 3]

By using the second compound 37 having this structure, the secondcompound 37 exhibits superior reactivity to the hydroxyl grouppositioned in the surface of the base particles 2.

Although the second compound 37 may have the non-polar group D directlyconnected to the silicon atom as represented by the general formula(III), an interposed matter such as a siloxane skeleton may beinterposed between the silicon atom and the non-polar group.

It is preferable that the molecular weight of the second compound 37 be100 or more to 1,000 or less, and 100 or more to 500 or less is morepreferable. Accordingly, the steric hindrance of the second compound 37is reduced and the second compound 37 can be more reliably interposed ina region between the first compound 39 and the third compound 35connected to the base particle 2. As a result, it is possible for thedispersibility of the electrophoretic particles 1 in the electrophoresisdispersion liquid to be made superior.

When the weight average molecular weight of the dispersion portion 32 isA and the molecular weight of the second compound 37 is B, it ispreferable that A/B be 10 or more to 1,000 or less, and 50 or more to500 or less is more preferable. Accordingly, it is possible for theeffects to be more remarkably exhibited.

It is preferable for the addition amount of the second compound 37 inthe electrophoretic particles 1 to the base particles 2 to be 0.1 wt %or more to 2.0 wt % or less, and 0.3 wt % or more to 1.0 wt % or less ismore preferable. Accordingly, it is possible for the effects to be moreremarkably exhibited.

As described above, the third compound 35 in the embodiment is a silanecoupling agent that includes a charging group and a second functionalgroup.

The third compound 35 has a lower molecular weight than the firstcompound 39, and is connected to the base particle 2 at the secondfunctional group by reacting the first functional group and the secondfunctional group.

The third compound 35 is a compound including a charging group.Accordingly, by setting, as appropriate, the type of the charging groupand further, the number of third compounds 35 connected to the baseparticle 2, it is possible to make the positive and negativechargeability of the electrophoretic particles 1, and further thecharging amount of the electrophoretic particles 1 desirable. That is,the third compound 35 is connected to the surface of the base particle 2in order to set the positive and negative chargeability of theelectrophoretic particles 1, and the charging amount thereof to bedesirable in the electrophoresis dispersion liquid.

Below, each portion (charging group and second functional group) thatforms the silane coupling agent having a charging group and a secondfunctional group that is the third compound 35 in the embodiment will bedescribed.

The charging group is provided on the surface of the base particle 2 inthe coating layer 3 in order to set the positive and negativechargeability of the electrophoretic particles 1, and the chargingamount thereof to be desirable in the electrophoresis dispersion liquid.

Although not particularly limited, as long as the charging groupexpresses positive or negative chargeability, examples thereof includepolarization groups or ionic groups. Accordingly, it is possible for thethird compound 35 to reliably provide positive or negativechargeability.

The polarization group from the charging group is an organic grouphaving a main skeleton, and a substituent bonded to the main skeleton.In the polarization group, by setting at least one condition of the typeof substituent (either or both of an electron absorbing group and anelectron donating group), number of bonds with respect to the mainskeleton, and the bonding position, the electrons in the main skeletonare biased (polarized), and thereby, the charge state of the thirdcompound 35 is controlled.

That is, on the end portion (below, referred to “terminal of the mainskeleton”) side of the opposite side to the second functional group ofthe main skeleton, the electrons are biased further toward the terminalend side than to the polymerizable group side of the main skeleton inthe polarization group in which the electron absorbing group (electronwithdrawing group) is bonded as a substituent. When such a polarizationgroup is introduced, the third compound 35 is negatively charged.

Meanwhile, on the second functional group side of the main skeleton, theelectrons are biased further to the second functional group side thanthe terminal side of the main skeleton in the polarization group inwhich the electron withdrawing group is bonded as a substituent. Whensuch a polarization group is introduced, the third compound 35 ispositively charged.

In the polarization group to which an electron donating group (electrondonor group) is bonded as a substituent, because an opposite bias in theelectron concentration to the above-described arises, when thepolarization group in which the electron donor group is bonded to theterminal side of the main skeleton is introduced, the third compound 35is positively charged, and when the polarization group in which theelectron donor group is bonded to the second functional group side ofthe main skeleton, the third compound 35 are negatively charged.

The bias in the electron concentration exhibits a tendency to increasingas the number of bonds of the substituent bonded to the main skeletonincreases.

It is possible to control (adjust) the third compound 35 to a desiredcharging state providing the third compound 35 with a polarization groupin which bias arises in this electron density.

It is preferable to be in a state in which the bias in electronconcentration easily arises in the main skeleton of the polarizationgroup. Accordingly, it is preferable that the main skeleton have aportion (structure) in which IC electrons are delocalized. Accordingly,the movement of electrons in the main skeleton easily arises, it ispossible for the biasing in the electron density to be more remarkablyexhibited.

Although the portions in which the IC electrons are delocalized are allpreferably in a structure in which the conjugated double bonds arelinearly connected, it is preferable to have a ring structure in whichat least a part thereof form a ring. Accordingly, the movement of theelectrons more easily and smoothly occurs.

Although various types of such a ring structure exist, it is preferablethat the ring structure be an aromatic ring, and it is particularlypreferable that the ring structure be a benzene ring, a naphthalenering, a pyridine ring, a pyrrole ring, a thiophene ring, an anthracenering, a pyrene ring, a perylene ring, a pentacene ring, a tetracenering, a chrysene ring, an azulene ring, a fluorene ring, a triphenelenering, a phenanthrene ring, a quinoline ring, an indole ring, a pyrazinering, an acridine ring, a carbazole ring, a furan ring, a pyran ring, apyrimidine ring, or a pyridazine ring. Accordingly, bias (polarization)in the electron concentration in the ring structure easily arises, and,as a result, it is possible for the bias in the electron concentrationto be made more remarkable.

It is preferable that the main skeleton further have the ring structureat the terminal thereof, and that the substituent be bonded to the ringstructure.

Accordingly, bias (polarization) in the electron concentration in thering structure easily arises, and, as a result, it is possible for thebias in the electron concentration to be made more remarkable.

It is preferable that the substituent in the third compound 35 be anelectron withdrawing group or an electron donor group.

Accordingly, it is possible for the third compound 35 to reliablyprovide positive or negative chargeability.

Here, a case of the main skeleton having a benzene ring at the terminalthereof is described as an example.

In this case, when the electron absorbing group T as the substituent isbonded to at least the three third to fifth positions (all of the secondto sixth positions in the following chemical formula (a)) from thesecond to sixth positions of the I: benzene ring, as illustrated in thefollowing chemical formula (a), the electrons in the main skeleton aredrawn to the terminal side by the presence of the electron absorbinggroup T, and biased. Therefore, the third compound 35 is negativelycharged.

When the electron absorbing group T as the substituent is bonded to atleast one position (in the following chemical formula (b), third andfourth positions) of the third, fourth, and fifth positions of the II:benzene ring, as illustrated in the following chemical formula (b), theelectrons in the main skeleton (in particular, on the benzene ring) aredrawn to the terminal side by the presence of the electron absorbinggroup T, and biased. Therefore, the third compound 35 is negativelycharged.

When the electron absorbing group T as the substituent is bonded to atleast one position (in the following chemical formula (c), second andsixth positions) of the second and sixth positions of the III: benzenering, as illustrated in the following chemical formula (c), theelectrons in the main skeleton (in particular, on the benzene ring) aredrawn to the polymerizable group side by the presence of the electronabsorbing group T, and biased. Therefore, the third compound 35 ispositively charged.

When the electron donating group G as the substituent is bonded to atleast the three third to fifth positions (in the following chemicalformula (d), four positions of second to fifth positions) from thesecond to sixth positions of the IV: benzene ring, as illustrated in thefollowing chemical formula (d), the electrons in the main skeleton aredrawn to polymerizable group side by the presence of the electrondonating group G, ad biased. Therefore, the third compound 35 ispositively charged.

When the electron donating group G as the substituent is bonded to atleast one position (in the following chemical formula (e), fourthposition) from the third, fourth, and fifth positions of the V: benzenering, as illustrated in the following chemical formula (e), theelectrons in the main skeleton (in particular, on the benzene ring) aredrawn to the polymerizable group side by the presence of the electrondonating group G, and biased. Therefore, the third compound 35 ispositively charged.

When the electron donating group G as the substituent is bonded to atleast one position (in chemical formula (f), second position) from thesecond and sixth positions of the VI: benzene ring, as illustrated inthe following chemical formula (f), the electrons in the main skeleton(in particular, on the benzene ring) are drawn to the terminal side bythe presence of the electron donating group G, and biased. Therefore,the third compound 35 is negatively charged.

It should be noted that the II structure and VI structure, and the IIIstructure and V structure, may be combined, respectively. Accordingly,it is possible for the bias in the electron concentration in the mainskeleton (in particular, on the benzene ring) to be still moreremarkable.

The main skeleton may be formed of only one ring structure describedabove, or may be a structure in which a plurality of ring structures arebonded in a straight chain. Specific examples of the latter mainskeleton include the following formulae (A-1) to (A-3)

wherein, in formulae (A-1) to (A-3), n in the formula indicates aninteger of 1 or more.

In the main skeleton represented by the formulae (A-1) to (A-3),although it is preferable that the substituent be bonded to the ringstructure of the terminal, the substituent may be bonded to another ringstructure other than the terminal.

The electron absorbing group T is not particularly limited if it is asubstituent that exhibits a tendency to be more strongly drawn(withdrawn) than hydrogen atoms, and examples thereof include halogenatoms, such as F, Cl, Br and I, a cyano group, a nitro group, a carboxylgroup, a trifluoromethyl group, a formyl group, and a sulfo group. Amongthese, it is preferable that the electron absorbing group be at leastone type selected from a group formed from a halogen atom, a cyanogroup, a nitro group, a carboxyl group, and a trifluoromethyl group.These have a particularly high capacity for drawing electrons.

Meanwhile, the electron donating group G is not particularly limited ifit is a substituent that exhibits a tendency toward strongly expelling(donating) electrons compared to hydrogen atoms, and examples thereofinclude an amino group, an alkyl group, an alkoxy group, and a hydroxylgroup. Among these, the electron donating group is at least one typeselected from a group formed from an amino group, an alkyl group, and analkoxy group. These have a particularly high capacity for expellingelectrons.

The alkyl group preferably has 1 to 30 carbon atoms, and more preferably1 to 18 carbon atoms. The alkoxy group preferably has 1 to 30 carbonatoms, and more preferably 1 to 18 carbon atoms. When the number ofcarbon atoms is excessively high in the alkyl group and the alkoxygroup, either one of the alkyl group and the alkoxy group exhibits atendency to easily aggregate to themselves, and, as a result, there isconcern of difficulty in adjusting the charging state of the thirdcompound 35 to a desired state.

It is preferable that the total number of carbon atoms in the mainskeleton be 6 to 40, and 6 to 35 is more preferable. When the totalnumber of carbon atoms is excessively low, the atoms do not easilybecome delocalized, and there is concern that it may therefore bedifficult for bias in the electrons to effectively arise, whereas, whenthe total number of carbon atoms is too high, there is concern of itbeing difficult to introduce the third compound 35 to the surface of thebase particles 2.

Examples of ionic group include those provided with a basic group, suchas an amino group, and thereby imparting positive chargeability to thethird compound 35 by exhibiting positive ionicity, and those providedwith an acidic group, such as a carboxy group, and thereby impartingnegative chargeability to the third compound 35 by exhibiting negativeionicity. Among these, those provided with an acidic group and furtherhaving a configuration provided with a cyclic structure which forms anacidic group and a salt are preferably used.

By using a group which has a cyclic structure, in which the cyclicstructure forms an acidic group and a salt as the ionic group, it ispossible for the third compound 35 to have superior solubility and to bedissolved in the solvent when preparing the electrophoretic particles,described later. A portion of the cyclic structure is dissociated fromthe acidic group in the electrophoresis dispersion liquid, and it ispossible for the electrophoretic particles 1 to have superiordispersibility caused thereby and to be dispersed in the electrophoresisdispersion liquid. Accordingly, below, a configuration provided with anacidic group and a cyclic structure which forms an acidic group and asalt as the ionic group will be described.

Examples of the acidic group include a sulfonate group, a phosphoricacid group, and an alkoxy group in addition to the carboxy group, andalthough it is possible to use one type or a combination of two or moretypes thereof, among these, a carboxy group, a phosphoric acid group anda sulfonate group are preferable. Accordingly, it is possible toreliably form a salt between within the cyclic structure.

The cyclic structure (ionophore) forms an acidic group having amonofunctional monomer component and a salt in a state that captures analkali metals such as Na and K and metal ions such as alkaline earthmetals, such as Mg, and Ca. By the cyclic structure forming an acidicgroup and a salt, it is possible for the dispersibility of the thirdcompound 35 to be further improved during manufacturing of theelectrophoretic particles 1, and to reliably negatively charge the thirdcompound 35 in the electrophoresis dispersion liquid.

Although preferable examples of the ionophore (cyclic structure) thoseincluding at least one of an oxygen atom, a nitrogen atom, and a sulfuratom (that is, the methylene groups are bonded to one another with theoxygen atom, the nitrogen atom, or the sulfur atom), and those formedonly of methylene groups (hydrocarbon rings), and, in particular, thosein which the methylene groups are connected to one another with theoxygen atom, the nitrogen atom, or the sulfur atom (heteroatom) arepreferable. Such an ionophore is preferable since the structure thereofhas an extremely high capturing capacity of capturing the metal ions.There are advantages in that the size of the ring (inside space) andsoftness of the ring are easily adjusted, and that it is possible tocomparatively easily to perform the synthesis of the ionophore.

Examples of an ionophore including such a heteroatom include crownether-based, aza crown-based, cryptand-based, sulfide-based(thioether-based), and propylene glycol-based ionophores.

Examples of the crown ether-based ionophore include 12-crown-4-ether,2-hexyl-12-crown-4-ether, 2-octyl-12-crown-4-ether,2-decyl-12-crown-4-ether, 2-dodecyl-12-crown-4-ether,2-tetradecyl-12-crown-4-ether, 15-crown-5-ether,2-butyl-15-crown-5-ether, 2-hexyl-15-crown-5-ether,2-dodecyl-15-crown-5-ether, 2-tetradecyl-15-crown-5-ether, 18-crown-6ether, 2-hexyl-18-crown-6 ether, 2-octyl-18-crown-6 ether,2-tetradecyl-18-crown-6 ether, 2,3-dioctyl-18-crown-6 ether,21-crown-7-ether, 2-decyl-21-crown-7-ether, 24-crown-8-ether,2-decyl-24-crown-8-ether, and 2-dodecyl-24-crown-8-ether.

Examples of the aza crown-based ionophore include1,4,7-tripropyl-1,4,7-triazacyclononane,2-decyl-1,4,7-tripropyl-1,4,7-triazacyclononane,1,4,7-tributyl-1,4,7-triazacyclononane,1,4,7,10-tetraoctyl-1,4,7,10-tetraazacyclododecane,1,4,7,10-tetra(decyl)-1,4,7,10-tetraazacyclododecane,1,4,7,10-tetra(dodecyl)-1,4,7,10-tetraazacyclododecane,1,4,7,10-tetra(hexadecyl)-1,4,7,10-tetraazacyclododecane,1,4,7,10,13-pentaoctyl-1,4,7,10,13-pentaaza cyclopentadecane,1,4,7,10,13-penta(decyl)-1,4,7,10,13-pentaaza cyclopentadecane,1,4,7,10,13,16-hexa(decyl)-1,4,7,10,13,16-hexa azacyclo octadecane,1,4,7,10,13,16-hexa(tetradecyl)-1,4,7,10,13,16-hexa azacyclo octadecane,and 1,4,7,10,13,16-hexa(hexadecyl)-1,4,7,10,13,16-hexa aza cyclooctadecane.

Examples of the cryptand-based ionophore include4,10,15-trioxa-1,7-diazabicyclo[5.5.5] heptadecane,3-tetradecyl-4,10,15-trioxa-1,7-diazabicyclo[5.5.5] heptadecane,4,7,13,18-tetraoxa-1,10-diazabicyclo[8.5.5] eicosane,5-decyl-4,7,13,16,21-pentaoxa-1,10-diazabicyclo[8.8.5] tricosane,4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8] hexacosane,5-tetradecyl-4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane, and 4,7,10,16,19,24,27-heptaoxa-1,13-diazabicyclo[11.8.8]nonacosane.

In the embodiment, as described above, the second functional group is analkoxysilyl group, and the first functional group included in the baseparticles 2 is a hydroxyl group.

By making the combination of such a hydroxyl group and an alkoxysilylgroup, since the reaction between the groups indicates superiorreactivity, it is possible for the bond of the third compound 35 to thesurface of the base particle 2 to be more reliably formed at the secondfunctional group.

Examples of the third compound 35 that includes the second functionalgroup include silane coupling agents represented by the followinggeneral formula (IV) when the charging group is E.

[in the formula, E represents a charging group, each R independentlyrepresents an alkyl group having 1 to 4 carbon atoms, and n representsan integer of 1 to 3]

By using the third compound 35 having this structure, the third compound35 exhibits superior reactivity to the hydroxyl group positioned in thesurface of the base particles 2.

Although the third compound 35 may be a compound with the charging groupE directly connected to the silicon atom, as illustrated in generalformula (IV), the compound may have an intermediate such as a siloxaneskeleton interposed between the silicon atom and the charging group, ormay have a non-polar group described by the second compound 37interposed between the silicon atom and the charging group.

It is preferable that the molecular weight of the third compound 35 be100 or more to 1,000 or less, and 100 or more to 500 or less is morepreferable. Accordingly, the steric hindrance of the third compound 35is reduced and the third compound 35 can be more reliably interposed ina region between the first compound 39 and the second compound 37connected to the base particle 2. As a result, it is possible to morereliably set the charging amount of the electrophoretic particles 1 to asuitable range.

When the weight average molecular weight of the dispersion portion 32 isA and the molecular weight of the third compound 35 is C, it ispreferable that A/C be 10 or more to 1,000 or less, and 50 or more to500 or less is more preferable. Accordingly, it is possible for theeffects to be more remarkably exhibited.

It is preferable for the addition amount of the third compound 35 in theelectrophoretic particles 1 to the base particles 2 to be 0.1 wt % ormore to 2.0 wt % or less, and 0.3 wt % or more to 1.0 wt % or less ismore preferable. Accordingly, it is possible for the effects to be moreremarkably exhibited.

The base particle 2 included in the electrophoretic particles 1 havepositive chargeability or negative chargeability, and further, chargingamount individual to the base particle 2 according to the type ofselected particle, that is, the type of pigment particle, resinparticle, composite particle or the like. Therefore, when a portion ofthe base particle is exposed without the portion being covered by thecoating layer in the electrophoretic particles, the positive andnegative chargeability and the charging amount derived from the baseparticle exert an influence on the positive and negative chargeabilityand the charging amount of the electrophoretic particles. Accordingly,it is necessary to consider the positive and negative chargeability andthe charging amount derived from the base particle in theelectrophoretic particles even if control of the positive and negativechargeability and the charging amount of the electrophoretic particles 1is attempted by adjusting the bonding amount (adsorption amount) withrespect to the base particle of the third compound provided withpositive and negative chargeability and a charging amount. Morespecifically, the particles have individual positive and negativechargeability and charging amounts as above according to the type ofbase particles, and the positive and negative chargeability and chargingamount derived from the base particle exposed in the electrophoreticparticles differ according to the type of base particle. Therefore, thethird compound connected to the base particle has a problem in that itis necessary to set, as appropriate, the bonding amount thereofaccording to the type of base particle selected, and time and effort arenecessary.

In contrast, in the invention, the first compound 39, second compound37, and third compound 35 are connected to the surface of the baseparticle 2, and accordingly, substantially the entire surface of thebase particle 2 is covered and the surface of the base particle 2 beingexposed is accurately suppressed. More specifically, the bonding amountsof the first compound 39 which contributes dispersibility and the thirdcompound 35 which contributes chargeability are set according to thedispersibility and the charging amount each is to impart to theelectrophoretic particles 1, and the first compound 39 and the thirdcompound 35 are connected to the surface of the base particles 2. Thesecond compound 37 which does not contribute dispersibility andchargeability is connected to be embedded in the surface of the baseparticle 2 exposed by the connection with the first compound 39 and thethird compound 35, and, accordingly, substantially the entire surface ofthe base particle 2 is covered by the coating layer 3. As above, becausethe surface of the base particle 2 being exposed is effectively reducedin the electrophoretic particles 1, the contribution of the positive andnegative chargeability and the charging amount of the base particle 2 tothe positive and negative chargeability and the charging amount of theelectrophoretic particles 1 is accurately suppressed or prevented. Inthis case, the positive and negative chargeability and the chargingamount included by the third compound is contributed with priority.Accordingly, the positive and negative chargeability and the chargingamount of the electrophoretic particles 1 can be controlled by adjustingthe type and bonding amount of the third compound 35 connected to thebase particle 2, and simplification of the time and effort whenmanufacturing the electrophoretic particles 1 is achieved.

Accordingly, because aggregation between the electrophoretic particles 1in the electrophoresis dispersion liquid is suppressed for theelectrophoretic particles 1, as described above, the second compound 37is connected to the surface of the base particle 2, and exhibits afunction as a covering portion which effectively suppresses or preventsthe surface of the base particle 2 being unnecessarily exposed and anadverse influence being exerted on the positive and negativechargeability and the charging amount of the electrophoretic particles1.

In light of the above, the electrophoretic particles 1 exhibit superiordispersibility, have the charging amount thereof set to a suitable rangeand have superior electrophoretic properties in the electrophoresisdispersion liquid by means of the first compound 39, the second compound37, and the third compound 35 being connected to the base particles 2.

As outlined above, it is possible for the electrophoretic particles 1 ofthe embodiment in which the first compound 39, the second compound 37,and the third compound 35 are connected to the surface of the baseparticles 2 to be manufactured as follows applying the method ofmanufacturing the electrophoretic particles of the invention.

Method of Manufacturing Electrophoretic Particle

The method of manufacturing the electrophoretic particles 1 includes astep of connecting a plurality of the third compounds 35 to the baseparticle 2 by the first functional group included in the base particles2 and the second functional group included in the third compound 35being reacted, a step of obtaining the first compound 39 in which thebonding portion 31 and the dispersion portion 32 are connected using themonomer M1 and the monomer M2 by living polymerization, a step ofconnecting the plurality of first compounds 39 to the base particles 2by the first functional group included in the base particles 2 and thesecond functional group included in the bonding portion 31 beingreacted, and a step of connecting the plurality of the second compounds37 to the base particle 2, thereby forming the coating layer 3 by meansof the first functional group included in the base particles 2 and thesecond functional group included in the second compound 37 beingreacted.

In the step of obtaining the first compound 39, although 1) the bondingportion 31 in which the second monomer M2 having the second functionalgroup is polymerized may be formed after the dispersion portion 32 inwhich the first monomer M1 is polymerized may be formed by livingradical polymerization using a polymerization initiator, or 2) thebonding portion 31 and the dispersion portion 32 may be formed in thisorder, here, a case were the plurality of first compounds 39 is formedwith the method in 1) will be described.

Below, each step will be described in detail.

[1] First, the plurality of third compound 35 is connected to the baseparticles 2 by the first functional group included in the base particles2 and the second functional group included in third compound 35 reactedand a chemical bond being formed therebetween (first step).

Examples of the process by which the third compound 35 is connected tothe base particle 2 include a dry method and a wet method illustratedbelow.

Dry Method

In the dry method, first, a solution is prepared by mixing the thirdcompound 35 and the base particles 2 in a suitable solvent. Minuteamounts of water, an acid or a base may be added to the solution, asnecessary, in order to promote the hydrolysis of the alkoxysilyl groupincluded in the third compound 35. Heating, light radiation or the likemay be performed, as necessary.

At this time, it is preferable that the volume of the solvent beapproximately 1 vol % or more to the volume of the base particles 2 toapproximately 20 vol % or less, and approximately 5 vol % or more toapproximately 10 vol % or less is more preferable. Accordingly, becauseit is possible for the chance of the third compound 35 contacting thebase particle 2 to be increased, it is possible for the bonding portion31 to be more reliably bonded to the surface of the base particles 2.

Next, after the third compound 35 is highly efficiently adsorbed to thesurface of the base particles 2 by dispersing with ultrasound waveradiation or stirring using a ball mill or a bead mill, or the like, thesolvent is removed.

Next, a chemical bond with the hydroxyl group exposed in the surface ofthe base particles 2 is formed by decomposing the alkoxysilyl groupwhile heating the powder obtained by removing the solvent in preferableconditions of 100° C. to 200° C. for an hour or more.

Next, the excess first compound 39 adsorbed to the surface of the baseparticles 2 without forming a chemical bond is removed by cleaning againseveral times in the solution while using a centrifuge.

It is possible for the third compound 35 to be connected to the baseparticles 2 by passing through the above steps.

Wet Method

In the wet method, first, a solution is prepared by mixing the thirdcompound 35 and the base particles 2 in a suitable solvent. Minuteamounts of water, an acid or a base may be added to the solution, asnecessary, in order to promote the hydrolysis of the alkoxysilyl groupincluded in the third compound 35. Heating, light radiation or the likemay be performed, as necessary.

At this time, it is preferable that the volume of the solvent beapproximately 1 vol % or more to the volume of the base particles 2 toapproximately 20 vol % or less, and approximately 5 vol % or more toapproximately 10 vol % or less is more preferable. Accordingly, becauseit is possible for the chance of the third compound 35 contacting thebase particle 2 to be increased, it is possible for the bonding portion31 to be more reliably bonded to the surface of the base particles 2.

Next, after the third compound 35 is highly efficiently adsorbed to thesurface of the base particles 2 by dispersing with ultrasound waveradiation or stirring using a ball mill or a bead mill, or the like, itis possible for the third compound 35 to be connected to the baseparticles 2 by a chemical bond with the hydroxyl group exposed in thesurface of the base particles 2 being formed by decomposing thealkoxysilyl group while heating the solvent in this state in preferableconditions of 100° C. to 200° C. for one hour or more.

Next, the excess first compound 39 adsorbed to the surface of the baseparticles 2 without forming a chemical bond is removed by cleaning againseveral times in the solution while using a centrifuge.

In either of the wet method and the dry method, the content of the thirdcompound 35 in the solvent which contains the adjusted third compound 35and base particles 2 is set, as appropriate, in response to the positiveand negative chargeability and the charging amount imparted to theelectrophoretic particles 1 to be obtained, and the adsorption rate ofthe third compound 35 to the base particle 2 (equilibrium constant ofthe reaction between the base particle 2 and the third compound 35).

It is possible to prepare the second compound 37 using various knownmethods.

[2] Next, a plurality of the first compound 39 in which the dispersionportion 32 is connected to the bonding portion 31 is generated (secondstep).

[2-1] First, the dispersion portion 32 in which the first monomer M1 ispolymerized is formed by living polymerization using a polymerizationinitiator.

Although example of the living polymerization method include livingradical polymerization, living cationic polymerization, or livinganionic polymerization, and among these, living radical polymerizationis preferable. It is possible for a reaction liquid or the like in whichthe reaction system is generated to be simply used by performing livingradical polymerization, and further, it is possible for the monomer M1to be polymerized with good control of the reaction.

According to the living radical polymerization, it is possible for themolecular weight distribution in the dispersion portion 32 to be easilyset to 1.2 or less, and as a result, it is possible for the obtainedelectrophoretic particles 1 to exhibit a uniform dispersion capacity inthe electrophoresis dispersion liquid.

Although examples of the living radical polymerization method includeatom transfer radical polymerization (ATRP), nitroxide-mediated radicalpolymerization (NMP), telluride-mediated polymerization (TERP), andreversible addition-fragmentation chain-transfer polymerization (RAFT),among these, reversible addition-fragmentation chain-transferpolymerization (RAFT) is preferable. According to the reversibleaddition-fragmentation chain-transfer polymerization (RAFT), it ispossible for the polymerization to be caused to proceed simply duringpolymerization of the monomer M1 without using a metal catalyst andwithout concern of metal contamination. It is possible for the molecularweight distribution in the dispersion portion 32 to be more easily setto 1.2 or less.

Although not particularly limited, examples of the polymerizationinitiator (radical polymerization initiator) include azo initiators suchas 2,2′-azobis isobutyronitrile (AIBN), 2,2′-azobis(4-methoxy-2,4-dimethyl valeronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate), 1,1′-azobis(cyclohexane-1-carbonitrile), 2,2′-azobis [2-(2-imidazolin-2-yl)propane] dihydrochloride, and 2,2′-azobis [2-(2-imidazolin-2-yl)propane], and persulfate salts such as potassium persulfate, andammonium persulfate.

In a case of using the reversible addition-fragmentation chain-transferpolymerization (RAFT), a chain transfer agent (RAFT agent) is used inaddition to the polymerization initiator. Although not particularlylimited, examples of the chain transfer agent include sulfur compoundshaving a functional group such as dithioester groups, trithiocarbamategroups, xanthate groups, and dithiocarbamate groups.

Specifically, examples of the chain transfer agent include compoundsrepresented by the following chemical formulae (1) to (7), and it ispossible to use one type or a combination of two or more types thereof.These compounds are preferably used in light of being comparativelyeasily obtained and the reaction being easily controlled.

Among these, it is preferable that the chain transfer agent be a2-cyano-2-propylbenzathioate represented by the above chemical formula(6). In so doing, it is possible for control of the reaction to be moreeasily performed.

In a case of using reversible addition-fragmentation chain-transferpolymerization (RAFT), although the ratio of the monomer M1, thepolymerization initiator, and the chain transfer agent are determined,as appropriate, in consideration of the polymerization rate of thedispersion portion 32 to be formed or the reactivity of the compoundsuch as the monomer M1, it is preferable that the mol ratio thereof bemonomer: polymerization initiator: chain transfer agent=500 to 5:5 to0.25:1. Accordingly, it is possible to set the length (polymerizationrate) of the dispersion portion 32 obtained by polymerizing the monomerM1 to a suitable magnitude, and possible to highly efficiently generatethe dispersion portion 32 with the molecular weight distribution easilyset to 1.2 or less.

Examples of the solvent for preparing the solution in which the monomerM1 is polymerized by living radical polymerization include water,alcohols such as methanol, ethanol, and butanol, hydrocarbons, such ashexane, octane, benzene, toluene, and xylene, ethers such as diethylether, and tretrahydrofuran, and esters such as ethyl acetate, andhalogenized aromatic monomer hydrocarbons such as chlorobenzene ando-dichlorobenzene, and it is possible for these to be used independentlyor as a mixed solvent.

It is preferable that the solution (reaction liquid) is subjected to adeoxidation treatment before initiating the polymerization reaction.Examples of the deoxidation treatment include a conversion or purgingtreatment after vacuum degassing with an inert gas such as argon gas ornitrogen gas.

It is possible to quickly and reliably perform polymerization reactionof the monomer by heating (temperature increase) the temperature of thesolution to a predetermined temperature during the polymerizationreaction of the monomer M1.

Although the heating temperature is not particularly limited and differsslightly according to the type and the like of the monomer M1,approximately 30 to 100° C. is preferable. It is preferable that theheating time (reaction time) be approximately 5 to 48 hours in a casewhere the heating temperature is in the above range.

When using the reversible addition-fragmentation chain-transferpolymerization (RAFT), fragments of the chain transfer agent used arepresent at one terminal (tip portion) of the dispersion portion 32. Inthe next step [2-2], the dispersion portion 32 including the fragmentsacts as a chain transfer agent during the reaction in which the bondingportion 31 is reacted with the dispersion portion 32.

[2-2] Next, the bonding portion 31 at which the second monomer M2including the second functional group which has reactivity with thefirst functional group included in the base particles 2 is polymerizedis formed so as to be connected to the dispersion portion 32.

Accordingly, the first compound 39 configured by a diblock copolymer inwhich the dispersion portion 32 and the bonding portion 31 are connectedis generated.

In step [2-2], a purification treatment (removal treatment) that removesimpurities such as unreacted monomer M1, solvent or polymerizationinitiator used in the step [2-1], and isolates and purifies thedispersion portion 32 may be performed, as necessary, before forming thebonding portion 31 using the monomer M2. Accordingly, the first compound39 obtained in the step [2-2] is made more uniform and with a higherpurity. The purification treatment is not particularly limited, andexamples thereof include a column chromatography method, arecrystalization method, and a re-precipitation method, and it ispossible to perform one type or a combination of two or more typesthereof.

As described above, when using the reversible addition-fragmentationchain-transfer polymerization (RAFT), fragments of the chain transferagent used are present at one terminal of the dispersion portion 32.Therefore, the bonding portion 31 with this configuration is formed bypreparing the solution containing the dispersion portion 32 obtainedwith the step [2-1] completed, the monomer M2, and the polymerizationinitiator, and again performing living polymerization initiator in thesolution.

It is possible for the same solvents exemplified in the step [2-1] to beused as the solvent used in this step, and it is possible for theconditions when the monomer M2 is polymerized in the solution to be thesame as the those exemplified as the conditions when the monomer M1 ispolymerized in the solution in the step [2-1].

[3] Next, the plurality of first compounds 39 is connected to the baseparticles 2 by the first functional group remaining on the baseparticles 2 to which the plurality of third compounds 35 is connectedand the plurality of second functional groups included in the bondingportion 31 being reacted and a chemical bond being formed therebetween(third step).

The same processes by which the third compound 35 is connected to thebase particles 2 are used as the processes in which the first compound39 is connected to the base particles 2 are used in the dry method andwet method given as examples in step [1].

[4] Next, the plurality of second compounds 37 is connected to the baseparticles 2 by the first functional group remaining on the baseparticles 2 to which the plurality of first compounds 39 and thirdcompounds 35 are connected and the second functional group included inthe second compound 37 being reacted and a chemical bond being formedtherebetween (fourth step).

It is possible to prepare the second compound 37 using various knownmethods.

Examples of the process by which the second compound 37 is connected tothe base particle 2 include a dry method and a wet method in the step[1] similarly to the process by which the third compound 35 is connectedto the base particle 2.

Accordingly, electrophoretic particles 1 in which substantially theentire base particle 2 is coated with the coating layer 3 are obtained.

It is possible to obtain purified electrophoretic particles 1 by passingthrough the above steps.

It should be noted that although a case was described of obtaining theelectrophoretic particle 1 by connecting the third compound 35 to thebase particle 2 in the step [1], connecting the first compound 39 to thebase particle 2 in the step [3], and connecting the second compound 37to the base particle 2 in the step [4], it is possible for the order inwhich the first compound 39, the second compound 37, and the thirdcompound 35 are connected to the base particle 2 to be switched to anarbitrary order. However, by the third compound 35 first being connectedto the base particle 2 as in the embodiment, it is possible to morereliably impart the charging amount to the electrophoretic particles 1as an advantage without errors arising.

There are cases of not being dispersed in the dispersion solvent whenthe electrophoretic particles 1 are dried according to the type of themonomer M1 included in the first compound 39. In such a case, it ispreferable convert the reaction solvent to the dispersion solvent alittle at a time (not passing through the drying step) with a solventconversion method during the cleaning task.

It is possible to use the aliphatic hydrocarbons (liquid paraffin) andthe silicone oil, or the like exemplified as the dispersion liquidincluded in the electrophoresis dispersion liquid, described later, inaddition to being able to use the same one exemplified in the step [2-1]as the solvent used in this step.

In the embodiment, a case where the second functional group included inthe first compound 39 and the second compound 37 are both an alkoxysilylgroup is described; however, the second functional group is selectedfrom various functional groups, as outlined above, as long as they areable to react and connect to the first functional group, in this case,the second functional group included in the first compound 39 and thesecond functional group included in the second compound 37 may be thesame as each other or may be different.

Second Embodiment

Next, the second embodiment of the electrophoretic particles of theinvention will be described.

FIG. 3 is a schematic view of the first compound, the second compound,and the third compound included in the second embodiment of theelectrophoretic particles of the invention.

Below, the electrophoretic particles of the second embodiment will bedescribed centering on the points of difference to the electrophoreticparticles 1 of the first embodiment, and similar matters will not bedescribed.

The electrophoretic particles 1 are the same as the electrophoreticparticles 1 of the first embodiment shown in FIG. 2 other than theconfiguration of the second compound and the third compound from thefirst compound, the second compound, and third compound bonded to thebase particles 2 being different, as illustrated in FIG. 3.

That is, in the electrophoretic particles 1 of the second embodiment,the second compound 38 is connected instead of the second compound 37,and the second compound 38 is a block copolymer including the non-polarportion 33 derived from a third monomer M3 including the non-polargroup, and a bonding portion 31 derived from the second monomer M2 thatincludes the second functional group. In the second compound 38 withthis configuration, the second compound 38 is connected to the baseparticles 2 by reacting the first functional group and the secondfunctional group at the bonding portion 31. In the electrophoreticparticles 1 of the second embodiment, the third compound 36 is connectedinstead of the third compound 35, and the third compound 36 is a blockcopolymer including charging portion 34 derived from a fourth monomer M4including the charging group, and a bonding portion 31 derived from thesecond monomer M2 that includes the second functional group. In thethird compound 36 with this configuration, the third compound 36 isconnected to the base particles 2 by reacting the first functional groupand the second functional group at the bonding portion 31.

The non-polar portion 33 included in the second compound 38, similarlyto the non-polar group included in the second compound 37 of the firstembodiment, is provided on the surface of the base particles 2 in thecoating layer 3 in order to suppress or prevent aggregation between theelectrophoretic particles 1 in the electrophoresis dispersion liquid,described later.

The non-polar portion 33 is formed by polymerizing a plurality of themonomers M3 having a site at which the non-polar group included in thesecond compound 37 of the first embodiment becomes a side-chain afterpolymerization in the electrophoresis dispersion liquid, and a pluralityof non-polar units derived from the monomer M3 are connected.

The monomer M3 includes one polymerizable group to be able to bepolymerized by live radical polymerization (radical polymerization), andafter further polymerization is a pendant-type monofunctional monomerthat includes a site that is a non-polar side-chain.

The non-polar portion 33 formed by live radical polymerization reliablyexhibits a function of suppressing or preventing aggregation between theelectrophoretic particles 1 in the electrophoresis dispersion liquid,described later, by using a monomer including a non-polar side chain asthe monomer M3. Therefore, the electrophoretic particles 1 that includethe non-polar portion 33 have superior dispersibility and are dispersedin the electrophoresis dispersion liquid without being aggregated.

It is possible to use a monomer including the non-polar group includedin the above-described second compound 37 as a side chain, instead ofthe side chain that contributes to dispersibility included in theabove-described monomer M1, as the monomer M3.

Although the bonding portion 31 is bonded to the surface of the baseparticles 2 in the coating layer 3 included in the electrophoreticparticles 1, and thereby, the second compound 38 is connected to thebase particles 2, it is possible to use a configuration similar to thatof the bonding portion 31 included in the first compound 39 as thebonding portion 31.

The charging portion 34 included in the third compound 36, similarly tothe charging group included in the third compound 35 of the firstembodiment is provided on the surface of the base particles 2 in thecoating layer 3 in order to suppress or prevent aggregation between theelectrophoretic particles 1 in the electrophoresis dispersion liquid,described later.

The charging portion 34 is formed by polymerizing a plurality ofmonomers M4 having a site at which the charging group included in thethird compound 35 of the first embodiment becomes a side-chain afterpolymerization in the electrophoresis dispersion liquid, and a pluralityof charging portions derived from the monomer M4 are connected.

The monomer M4 includes one polymerizable group that is able to bepolymerized by live radical polymerization (radical polymerization), andafter further polymerization is a pendant-type monofunctional monomerthat includes a site that is a chargeable side-chain.

The charging portion 34 formed by live radical polymerization reliablyexhibits a function of imparting chargeability to the electrophoreticparticles 1 in the electrophoresis dispersion liquid, described later,by using a monomer including a chargeable side chain as the monomer M4.Therefore, the electrophoretic particles 1 which include the chargingportion 34 in the electrophoresis dispersion liquid are provided withthe positive and negative chargeability and charging amount that is anadvantage.

It is possible to use a monomer including the charging group included inthe above-described third compound 35 as a side chain, instead of theside chain that contributes to dispersibility included in theabove-described monomer M1, as the monomer M4.

Although the bonding portion 31 is bonded to the surface of the baseparticles 2 in the coating layer 3 included in the electrophoreticparticles 1, and thereby, the third compound 36 is connected to the baseparticles 2, it is possible to use the same configuration as that of thebonding portion 31 included in the first compound 39 as the bondingportion 31.

Similar effects to the first embodiment are obtained even by suchelectrophoretic particles of the second embodiment provided with thesecond compound 38 formed of a block copolymer having a non-polarportion 33 and a bonding portion 31 and a third compound 36 formed of ablock copolymer having a charging portion 34 and a bonding portion 31.

Electrophoresis Dispersion Liquid

Next, the electrophoresis dispersion liquid of the invention will bedescribed.

The electrophoresis dispersion liquid is a liquid in which at least onetype of electrophoretic particle (electrophoretic particles of theinvention) is dispersed (suspended) in a dispersion medium (liquid phasedispersion medium).

It is preferable that a dispersion medium having a boiling point of 100°C. or more and comparatively high insulation properties be used.Examples of the dispersion medium include various types of water (forexample, distilled water, pure water, and the like), alcohols such asbutanol and glycerin, cellosolves such as butyl cellosolve, esters suchas butyl acetate, ketones such as dibutyl ketones, aliphatichydrocarbons such as pentane (liquid paraffin), alicyclic hydrocarbonssuch as cyclohexane, aromatic hydrocarbons such as xylene, halogenatedhydrocarbons such as methylene chloride, aromatic heterocycles such aspyridine, nitriles such as acetonitrile, amides such as N,N-dimethylformamide, carboxylic acid salt, and silicone oil, or various othertypes of oil, and these may be used independently or as a mixture.

Among these, a dispersion medium having aliphatic hydrocarbons (liquidparaffin), or silicone oil as a main component is preferable. Since thedispersion medium having liquid paraffin or silicone oil as a maincomponent has a high aggregation suppression effect on theelectrophoretic particles 1, it is possible suppress deterioration overtime of the display performance of the electrophoresis display device920 shown in FIG. 4. Liquid paraffin or silicone oil has excellentweather resistance because of not having unsaturated bonds, and has thefurther advantage of high safety.

It is preferable for a dispersion medium with a relative dielectricconstant of 1.5 or more to 3 or less to be used, and 1.7 or more to 2.8or less is more preferable. The dispersion medium has superiordispersibility of the electrophoretic particles 1, and also hasexcellent electrical insulation properties. Therefore, this contributesto realizing an electrophoresis display device 920 with a reduced powerconsumption and capable of high contrast display. The value of thedielectric constant is a value measured at 50 Hz, and is a valuemeasured for the dispersion medium for which the contained moisturecontent at 25° C. is 50 ppm or less.

Various additives such as charge control agents composes of particles,such as an electrolyte, a surfactant (anionic or cationic), a metallicsoap, a resin material, a rubber material, a petroleum, a varnish, or acompound, a lubricant, a stabilizer, and various dyes may be added tothe dispersion medium as necessary.

Dispersion of the electrophoretic particles in the dispersion medium ispossible by performing one or a combination of two or more types from apaint shaker method, a ball mill method, an ultrasound dispersion methodor a stirring dispersion method, or the like.

The electrophoretic particles 1 exhibit a superior dispersion capacitythrough the action of the first compound 39 included in the coatinglayer 3 in the electrophoresis dispersion liquid.

Electrophoresis Display Device

Next, the electrophoresis display device to which the electrophoresissheet of the invention is applied (electrophoresis device of theinvention) will be described.

FIG. 4 is a view schematically showing a longitudinal cross-section ofthe embodiment of the electrophoresis display device and FIGS. 5 and 6are schematic views showing an operation principle of theelectrophoresis display device shown in FIG. 4. Below, for ease ofdescription, description will be provided with the upper side in FIGS. 4to 6 as “up” and the lower side as “down”.

The electrophoresis display device 920 shown in FIG. 4 includes anelectrophoresis display sheet (front plane) 921, a circuit substrate(back plane) 922, an adhesive layer 98 that bonds the electrophoresisdisplay sheet 921 and the circuit substrate 922, and a sealing portion97 that hermetically seals the gap between the electrophoresis displaysheet 921 and the circuit substrate 922.

The electrophoresis display sheet (electrophoresis sheet of theinvention) 921 includes a substrate 912 provided with a plate-like baseportion 92 and a second electrode 94 provided on the lower surface ofthe base portion 92 and a display layer 9400 which is provided on thelower surface (one surface) of the substrate 912 and configured by adividing wall 940 formed in a matrix, and the electrophoresis dispersionliquid 910.

Meanwhile, the circuit substrate 922 includes a counter substrate 911provided with a plate-like base portion 91 and a plurality of firstelectrodes 93 provided on the upper surface of the base portion 91, acircuit (not shown) which is provided on the counter substrate 911 (baseportion 91) and includes a switching element such as a TFT, and adriving IC (not shown) by which the switching element is driven.

Below, the configuration of each portion will be sequentially described.

The base portions 91 and 92 are respectively configured by sheet-like(flat plate-like) members, and each member arranged therebetween has asupporting and protecting function.

Although each base portion 91 and 92 may be either flexible or hard,flexible is preferable. By using flexible base portions 91 and 92, it ispossible to obtain a flexible electrophoresis display device 920, thatis, an electrophoresis display device 920 useful in the construction ofelectronic paper.

In a case where each base portion (base material layer) 91 and 92 haveflexibility, it is preferable that these each be configured by a resinmaterial.

The average thickness of the base portions 91 and 92 are each set, asappropriate, according to the constituent materials, usage or the like,and although not particularly limited, approximately 20 to 500 μm ispreferable, and approximately 25 to 250 μm is more preferable.

A layered (film-like) first electrode 93 and second electrode 94 arerespectively provided on the surface of the dividing wall 940 side ofthe base portions 91 and 92, that is, on the upper surface of the baseportion 91 and the lower surface of the base portion 92.

When a voltage is applied between the first electrode 93 and the secondelectrode 94, an electric field arises therebetween, and the electricfield acts on the electrophoretic particles (electrophoretic particlesof the invention) 95.

In the embodiment, the second electrode 94 is the common electrode, andthe first electrode 93 is an individual electrode (pixel electrodeconnected to the switching element) divided in a matrix-shape (gridshape), and the parts where the second electrode 94 and one firstelectrode 93 configure one pixel electrode.

The constituent material of each electrode 93 and 94 is not particularlylimited as long as each substantially has conductivity.

The average thickness of the electrodes 93 and 94 are each set, asappropriate, according to the constituent materials, usage or the like,and although not particularly limited, approximately 0.05 to 10 μm ispreferable, and approximately 0.05 to 5 μm is more preferable.

From each of the base portions 91 and 92 and each of the electrodes 93and 94, the base portion and electrode (in the embodiment, the baseportion 92 and the second electrode 94) disposed at the display surfaceside each have optical transparency, that is, are made substantiallytransparent (colorless and transparent, colored and transparent, ortranslucent).

In the electrophoresis display sheet 921, the display layer 9400 isprovided in contact with the lower surface of the second electrode 94.

The display layer 9400 is configured so that the electrophoresisdispersion liquid (the above-described electrophoresis dispersion liquidof the invention) 910 is accommodated (sealed) in the plurality of pixelspaces 9401 defined by the dividing wall 940.

The dividing wall 940 is formed between the counter substrate 911 andthe substrate 912 so as to be divided in a matrix-form.

Examples of the constituent material of the dividing wall 940 includevarious types of resin materials such as thermoplastic resins, such asacrylic resins, urethane resins, and olefin resins, and heat-curableresins, such as epoxy resins, melamine resins, and phenolic resins, andit is possible to use one type or a combination of two or more kindsthereof.

The electrophoresis dispersion liquid 910 accommodated in the pixelspace 9401, in the embodiment, is a liquid in which two types of coloredparticles 95 b and white particles 95 a (at least one type ofelectrophoretic particles 1) are dispersed (suspended) in a dispersionmedium 96, and the above-described electrophoresis dispersion liquid ofthe invention is applied.

In the electrophoresis display device 920, when a voltage is appliedbetween the first electrode 93 and the second electrode 94, the coloredparticles 95 b and the white particles 95 a (electrophoretic particles1) undergo electrophoresis toward either electrode according to theelectric field arising therebetween.

In the embodiment, particles having a negative charge are used as thewhite particles 95 a and particles having a positive charge are used asthe colored particles (black particles) 95 b. That is, electrophoreticparticles 1 in which the base particles 2 are negatively (minus) chargedare used as the white particles 95 a and electrophoretic particles 1 inwhich the base particles 2 are positively (plus) charged are used as thecolored particles 95 b.

In a case of using such electrophoretic particles 1, when the firstelectrode 93 has a positive potential, the colored particles 95 b moveto the second electrode 94 side and gather at the second electrode 94 asillustrated in FIG. 5 Meanwhile, the white particles 95 a move to thefirst electrode 93 side and gather on the first electrode 93. Therefore,when the electrophoresis display device 920 is seen from above (displaysurface side), the color of the colored particles 95 b is visible, thatis, black is visible.

Conversely, when the first electrode 93 has a negative potential, thecolored particles 95 b move to the first electrode 93 side and gather atthe first electrode 93, as illustrated in FIG. 6 Meanwhile, the whiteparticles 95 a move to the second electrode 94 side and gather on thesecond electrode 94. Therefore, when the electrophoresis display device920 is seen from above (display surface side), the color of the whiteparticles 95 a is visible, that is, white is visible.

In such a configuration, by setting the charging amounts of the whiteparticle 95 a and the colored particles 95 b (electrophoretic particles1), the polarity of the electrode 93 or 94, and the potential betweenthe electrodes 93 and 94, as appropriate, desired information (image) isdisplayed on the display surface side of the electrophoresis displaydevice 920 according to the color combination of the white particles 95a and the colored particles 95 b, and the number and the like ofparticles that gather at the electrodes 93 and 94.

It is preferable for the specific gravity of the electrophoreticparticles 1 to be set to be substantially the same as the specificgravity of the dispersion medium 96. In so doing, it is possible for theelectrophoretic particles 1 to retain a fixed position in the dispersionmedium 96 for a long period of time even after the application of thevoltage between the electrodes 93 and 94 is stopped. That is, theinformation displayed on the electrophoresis display device 920 is heldfor a long period of time.

It is preferable that the average particle diameter of theelectrophoretic particles 1 be approximately 0.1 to 10 μm, andapproximately 0.1 to 7.5 μm is more preferable. By having the averageparticle diameter of the electrophoretic particles 1 in the above range,it is possible to reliably prevent aggregation between theelectrophoretic particles 1 or precipitation in the dispersion medium96, and as a result, it is possible to favorably prevent deteriorationof the display quality of the electrophoresis display device 920.

In the embodiment, the electrophoresis display sheet 921 and the circuitsubstrate 922 are bonded via the adhesive layer 98. Accordingly, it ispossible for the electrophoresis display sheet 921 and the circuitsubstrate 922 to be more reliably fixed.

Although the average thickness of the adhesive layer 98 is notparticularly limited, approximately 1 to 30 μm is preferable, andapproximately 5 to 20 μm is more preferable.

The sealing portion 97 is provided between the base portions 91 and 92along the edge portions thereof. Each electrode 93 and 94, the displaylayer 9400, and the adhesive layer 98 are hermetically sealed by thesealing portion 97. Accordingly, it is possible for moisture to beprevented from infiltrating into the electrophoresis display device 920and to more reliably prevent the deterioration of the displayperformance of the electrophoresis display device 920.

It is possible for the same materials as the examples of the constituentmaterials of the above-described dividing wall 940 to be used as theconstituent material of the sealing portion 97.

Electronic Apparatus

Next, the electronic apparatus of the invention will be described.

The electronic apparatus of the invention is provided with theelectrophoresis display device 920 as described above.

Electronic Paper

First, an embodiment of a case where the electronic apparatus of theinvention is applied to electronic paper will be described.

FIG. 7 is a perspective view illustrating an embodiment of a case wherethe electronic apparatus of the invention is applied to an electronicpaper.

The electronic paper 600 shown in FIG. 7 is provided with a main body601 formed of a rewritable sheet having the same texture and flexibilityas paper, and a display unit 602.

In the electronic paper 600, the display unit 602 is configured by theelectrophoresis display device 920 as described above.

Display

Next, an embodiment of a case where the electronic apparatus of theinvention is applied to a display will be described.

FIGS. 8 and 9 are views showing an embodiment of a case where theelectronic apparatus of the invention is applied to a display. Amongthese, FIG. 8 is a cross-sectional view, and FIG. 9 is a plan view.

The display (display device) 800 shown in FIGS. 8 and 9 is provided witha main body unit 801, and an electronic paper 600 provided to be freelydetachable with respect to the main body unit 801.

The main body unit 801 has an insertion port 805 allowing insertion ofthe electronic paper 600 formed in the side thereof (right side in FIG.8), and is also provided with two sets of transport roller pairs 802 aand 802 b in the interior thereof. When the electronic paper 600 isinserted inside the main body unit 801 through the insertion port 805,the electronic paper 600 is placed in the main body unit 801 in a stateof being pinched by the transport roller pairs 802 a and 802 b.

A rectangular hole portion 803 is formed in the display surface side ofthe main body unit 801 (front side of the paper surface in FIG. 9) and atransparent glass plate 804 is fitted into the hole portion 803.Accordingly, it is possible to view the electronic paper 600 in a stateof being placed in the main body unit 801 from outside the main bodyunit 801. That is, the display surface in the display 800 is configuredby the electronic paper 600 placed in the main body unit 801 beingviewed through the transparent glass plate 804.

A terminal unit 806 is provided on the insertion direction tip portionof the electronic paper 600 (in FIG. 8, the left side), and a socket 807to which the terminal unit 806 is connected in a state in which theelectronic paper 600 is placed in the main body unit 801 is provided inthe interior of the main body unit 801. A controller 808 and anoperation unit 809 are electrically connected to the socket 807.

In the display 800, the electronic paper 600 is placed in the main bodyunit 801 to be freely detachable, and may be carried and used in a stateof being removed from the main body unit 801.

In the display 800, the electronic paper 600 is configured by theelectrophoresis display device 920 as described above.

The electronic apparatus of the invention is not limited to applicationto those described above and examples include televisions, viewfinder-type or direct-view monitor-type video tape recorders, carnavigation systems, pagers, electronic organizers, calculators,electronic newspapers, word processors, personal computers,workstations, video phones, POS terminals, electronic apparatusesprovided with a touch panel, such as smartphones, tablet terminals,clocks, watches, and wearable devices, and the electrophoresis displaydevice 920 can be applied the display unit of these various electronicapparatuses.

Above, although the electrophoretic particles, the method ofmanufacturing electrophoretic particles, the electrophoresis dispersionliquid, the electrophoresis sheet, the electrophoresis device, and theelectronic apparatus of the invention were described based in theembodiments shown in the drawings, the invention is not limited theretoand the configuration of each part may be changed to an arbitraryconfiguration having the same function. Other arbitrary configurationsmay be added to the invention.

One or two or more steps with an arbitrary purpose may be added to themethod of manufacturing of the electrophoretic particles of theinvention.

EXAMPLES

Next, specific examples the invention will be described.

Method of Manufacturing Electrophoretic Particle, Preparation ofElectrophoresis Dispersion Liquid and Evaluation of ElectrophoresisDispersion Liquid 1. Synthesis of First Compound (Block Copolymer) 1-1.Synthesis of Dispersion Portion

60 g of a silicone macromonomer (“Silaplane FM-0726”, manufactured byJNC Corporation) with a molecular weight of 16,000, 250 mg of2-cyano-2-propylbenzodithioate, and 100 mg of azobis isobutyronitrilewere added to a flask, and, after the system was nitrogen converted,22.5 mL of ethyl acetate was further added, and thereafter, stirredwhile heated at 75° C. for 8 hours to polymerize a siliconemacromonomer. This was cooled to room temperature to finish thereaction, and the solvent removed to obtain a silicone polymer reactionsolution.

The obtained reaction solution was purified with a silica gel columnwith the mixed solvent of hexane and chloroform as a developing solvent,and the impurities removed to isolate the silicone polymer. It wasconfirmed by gel permeation chromatography with toluene as thedeveloping solvent that the result of measuring the weight averagemolecular weight (Mw) of the obtained silicone polymer was 48,000.

1-2. Synthesis of Bonding Portion

27.5 mg of azobisisobutyronitrile and 200 mg of3-methacryloxypropyltriethoxysilane (“KBE-503”, manufactured byShin-Etsu Silicone Co., Ltd.) were added to 10 g of the silicone polymerobtained above in a flask, and, after the system was nitrogen converted,ethyl acetate was further added, and thereafter, polymerization wasperformed while heating and stirring at 75° C. for 4 hours. This wascooled to room temperature to finish the reaction, and the solventremoved to obtain the first compound (block copolymer) in which thedispersion portion and the bonding portion are connected.

2. Synthesis of Third Compound

4.5 g of 3-(trimethoxysilyl)propylamine (manufactured by Tokyo ChemicalIndustry Co., Ltd., Mw 179.3) was added dropwise to a flask in which 4.5g of 4-tert-butylbenzoic acid (manufactured by Tokyo Chemical IndustryCo., Ltd., Mw: 178.2), 3.9 g of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC, manufactured by TokyoChemical Industry Co., Ltd., Mw 155.3) as a condensation agent forforming an amide bond, 0.6 g of 4-(dimethyl amino)pyridine (DMAP,manufactured by Tokyo Chemical Industry Co., Ltd., Mw 122.2), and 20 mLof anhydrous methylene chloride were mixed, and stirred for five hours.Accordingly, the amino group and the carboxylic acid were condensed. Theobtained reaction product was purified with a silica gel column and thethird compound was obtained.

3. Preparation of Electrophoresis Dispersion Liquid Including WhiteParticles (Positively Charged Particles) Example 1A

First, 0.10 g of the obtained third compound and 60 g of titanium oxideparticles with an average particle diameter of 250 nm (manufactured byIshihara Sangyo Kaisha, Ltd., “CR-50”) were mixed in 300 mL of toluene,and, after being subjected to ultrasound processing for one hour, heatedunder reflux for four hours at 130° C. Thereafter, after the particleswere washed with toluene, removing the unreacted third compound, theremaining toluene was dried and distilled, and white electrophoreticparticles to which the third compound is bonded were obtained.

Next, 60 g of the white electrophoretic particles was added to thesilicone oil (manufactured by Shin-Etsu Silicon Corporation, “KF-96-20cs”), and, after 12 g of the obtained first compound (block copolymer)and 1.2 g of n-butyltrimethoxy silane (manufactured by Gelest Inc., “SIB1988”, Mw 178.3) as the second compound were added and subjected toultrasound processing for one hour, heating and stirring were performedfor four hours at 180° C., thereby obtaining electrophoretic particlesin which the first compound and the second compound were connected tothe particle. The electrophoresis dispersion liquid including the whiteparticles was obtained by removing the unreacted first and secondcompounds from the post-reaction solution and substituting the siliconeoil with “KF-96L-2cs” manufactured by Shin-Etsu Chemical Co., Ltd.

The addition amounts of the first, second, and third compounds in theobtained electrophoretic particles were 2.5 wt %, 1.0 wt % and 0.1 wt %,respectively, to the titanium oxide particles.

Example 2A

Other than adding 0.40 g of the third compound, the electrophoresisdispersion liquid including the white particles was obtained similarlyto Example 1A.

The addition amounts of the first, second, and third compounds in theobtained electrophoretic particles were 2.5 wt %, 1.0 wt %, and 0.3 wt%, respectively, to the titanium oxide particles.

Example 3A

Other than adding 1.50 g of the third compound, the electrophoresisdispersion liquid including the white particles was obtained similarlyto Example 1A.

The addition amounts of the first, second, and third compounds in theobtained electrophoretic particles were 2.5 wt %, 1.0 wt %, 1.0 wt %,respectively, to the titanium oxide particles.

Example 4A

Other than adding 0.40 g of the third compound, and further adding 0.1 gof the second compound, the electrophoresis dispersion liquid includingthe white particles was obtained similarly to Example 1A.

The addition amounts of the first, second, and third compounds in theobtained electrophoretic particles were 2.5 wt %, 0.1 wt %, and 0.3 wt%, respectively, to the titanium oxide particles.

Example 5A

Other than adding 0.40 g of the third compound, and further adding 10 gof 1,1,1,3,3,3-hexamethyl disilazane (HMDS, manufactured by TokyoChemical Industry Co., Ltd., Mw 161.4) instead of n-butyltrimethoxysilane as the second compound, the electrophoresis dispersionliquid including the white particles was obtained similarly to Example1A.

The addition amounts of the first, second, and third compounds in theobtained electrophoretic particles were 2.5 wt %, 1.0 wt %, and 0.3 wt%, respectively, to the titanium oxide particles.

Example 6A

Other than adding 0.40 g of the third compound, and further adding 1 gof HMDS as the second compound, the electrophoresis dispersion liquidincluding the white particles was obtained similarly to Example 1A.

The addition amounts of the first, second, and third compounds in theobtained electrophoretic particles were 2.5 wt %, 0.1 wt %, and 0.3 wt%, respectively, to the titanium oxide particles.

Comparative Example 1A

Other than not adding the second compound, and omitting bonding of thesecond compound to the titanium oxide particles, the electrophoresisdispersion liquid including the white particles was obtained similarlyto Example 2A.

Comparative Example 2A

Other than not adding the second and third compounds, and omittingbonding of the second and third compounds to the titanium oxideparticles, the electrophoresis dispersion liquid including the whiteparticles was obtained similarly to Example 1A.

4. Preparation of Electrophoresis Dispersion Liquid Including BlackParticles (Negatively Charged Particles) Example 1B

0.10 g of the third compound (3,3,3-trifluoropropyl)trimethoxysilane(manufactured by Gelest Inc., “SIT 8372.0”, Mw 218.3) and 50 g oftitanium nitride particles (manufactured by Mitsubishi MaterialsCorporation, “SC13MT”) were mixed in 250 mL of toluene, and, after beingsubjected to ultrasound processing for one hour, heating under refluxwas performed for four hours at 130° C. Thereafter, after the particleswere washed with toluene, removing the unreacted third compound, theremaining toluene was dried and distilled, and black electrophoreticparticles to which the third compound is bonded were obtained.

Next, 50 g of the black electrophoretic particles was added to thesilicone oil (manufactured by Shin-Etsu Silicon Corporation, “KF-96-20cs”), and, after 20 g of the obtained first compound (block copolymer)and 1.2 g of n-butyltrimethoxy silane as the second compound were addedand subjected to ultrasound processing for one hour, heating andstirring were performed for four hours at 180° C., thereby obtainingelectrophoretic particles in which the first compound and the secondcompound were connected to the particle.

The electrophoresis dispersion liquid including the black particles wasobtained by removing the unreacted first and second compounds from thepost-reaction solution and substituting the silicone oil with“KF-96L-2cs” manufactured by Shin-Etsu Chemical Co., Ltd.

The addition amounts of the first, second, and third compounds in theobtained electrophoretic particles were 4.5 wt %, 1.0 wt % and 0.1 wt %,respectively, to the titanium nitride particles.

Example 2B

Other than adding 0.40 g of the third compound, the electrophoresisdispersion liquid including the black particles was obtained similarlyto Example 1B.

The addition amounts of the first, second, and third compounds in theobtained electrophoretic particles were 4.5 wt %, 1.0 wt % and 0.3 wt %,respectively, to the titanium nitride particles.

Example 3B

Other than adding 1.50 g of the third compound, the electrophoresisdispersion liquid including the black particles was obtained similarlyto Example 1B.

The addition amounts of the first, second, and third compounds in theobtained electrophoretic particles were 4.5 wt %, 1.0 wt % and 1.0 wt %,respectively, to the titanium nitride particles.

Example 4B

Other than adding 0.40 g of the third compound, and further adding 0.1 gof the second compound, the electrophoresis dispersion liquid includingthe black particles was obtained similarly to Example 1B.

The addition amounts of the first, second, and third compounds in theobtained electrophoretic particles were 4.5 wt %, 0.1 wt % and 0.3 wt %,respectively, to the titanium nitride particles.

Example 5B

Other than adding 0.40 g of the third compound, and further adding 10 gof HMDS instead of n-butyl trimethoxysilane as the second compound, theelectrophoresis dispersion liquid including the black particles wasobtained similarly to Example 1B.

The addition amounts of the first, second, and third compounds in theobtained electrophoretic particles were 4.5 wt %, 1.0 wt % and 0.3 wt %,respectively, to the titanium nitride particles.

Example 6B

Other than adding 0.40 g of the third compound, and further adding 1 gof HMDS as the second compound, the electrophoresis dispersion liquidincluding the black particles was obtained similarly to Example 1B.

The addition amounts of the first, second, and third compounds in theobtained electrophoretic particles were 4.5 wt %, 0.1 wt % and 0.3 wt %,respectively, to the titanium nitride particles.

Comparative Example 1B

Other than not adding the second compound, and omitting bonding of thesecond compound to the titanium nitride particles, the electrophoresisdispersion liquid including the black particles was obtained similarlyto Example 2B.

Comparative Example 2B

Other than not adding the second and third compounds, and omittingbonding of the second and third compounds to the titanium nitrideparticles, the electrophoresis dispersion liquid including the blackparticles was obtained similarly to Example 1B.

5. Preparation of Electrophoresis Dispersion Liquid Including WhiteParticles and Black Particles

An electrophoresis dispersion liquid including white particles and blackparticles mixed so that the white and black particles are combined, andthe volume ratio of the white electrophoresis dispersion liquid and theblack electrophoresis dispersion liquid is 10:1, for the electrophoresisdispersion liquid containing the white particles of Examples 1A to 6Aand Comparative Examples 1A and 2A and the electrophoresis dispersionliquid including the black particles of Examples 1B to 6B andComparative Examples 1B and 2B.

6. Evaluation of Electrophoresis Dispersion Liquid

6-1.

First, the dispersibility and migration characteristics as below wereevaluated for each of the electrophoresis dispersion liquids prepared inthe above 3. to 4.

Evaluation of Dispersibility

That is, first, a comb electrode substrate for evaluation on which acomb electrode with an inter-electrode distance of 100 μm is formed wasprepared on a glass substrate.

Next, after diluting the electrophoresis dispersion liquid so that thecontent rate of the electrophoretic particles is 1 wt %, the dilutedelectrophoresis dispersion liquid was added dropwise onto the combelectrode of the comb electrode substrate for evaluation.

Next, the drop-wise added electrophoresis dispersion liquid was observedusing a microscope.

The results thereof were evaluated based on the evaluation criteriashown below.

Evaluation Standards

A: Aggregation of the electrophoretic particles in the electrophoresisdispersion liquid is not identified, and the electrophoretic particlesare evenly spread in the electrophoresis dispersion liquid.

B: Slight aggregation of the electrophoretic particles identified in theelectrophoresis dispersion liquid.

C: Partial aggregation of the electrophoretic particles identified inthe electrophoresis dispersion liquid.

D: Large amounts of aggregation of the electrophoretic particlesidentified in the electrophoresis dispersion liquid.

Evaluation of Migration Properties

Next, 15 V was applied between the comb electrodes in a state with theelectrophoresis dispersion liquid added dropwise on the comb electrodesubstrate, and the migration properties of the electrophoretic particlesat this time were observed using a microscope.

The results thereof were evaluated based on the evaluation criteriashown below.

Evaluation Standards

4: The electrophoretic particles in the electrophoresis dispersionliquid migrated extremely quickly.

3: The electrophoretic particles in the electrophoresis dispersionliquid migrated quickly.

2: The electrophoretic particles in the electrophoresis dispersionliquid migrated slowly.

1: Reverse charged electrophoretic particles were mixed in theelectrophoresis dispersion liquid. Alternatively, there wassubstantially no migration.

The evaluation results thereof are illustrated in Tables 1 and 2.

TABLE 1 Particles First Compound Second Compound Third CompoundEvaluation (White First Second Addition Addition Migration Particles)Monomer Monomer Type Amount (wt %) Type Amount (wt %) DispersibilityProperties Example 1A CR50 16k Siloxane KBE-503 n-butyl 1.0 Third 0.1 B2 MA trimethoxysilane Compound Example 2A CR50 16k Siloxane KBE-503n-butyl 1.0 synthesized in 0.3 A 3 MA trimethoxysilane 2. Example 3ACR50 16k Siloxane KBE-503 n-butyl 1.0 1.0 A 4 MA trimethoxysilaneExample 4A CR50 16k Siloxane KBE-503 n-butyl 0.1 0.3 A 3 MAtrimethoxysilane Example 5A CR50 16k Siloxane KBE-503 hexamethyl 1.0 0.3A 3 MA disilazane Example 6A CR50 16k Siloxane KBE-503 hexamethyl 0.10.3 A 3 MA disilazane Comparative CR50 16k Siloxane KBE-503 — — 0.3 B 3Example 1A MA Comparative CR50 16k Siloxane KBE-503 — — — — C 1 Example2A MA

TABLE 2 Second Compound Third Compound Particles First Compound AdditionAddition Evaluation (Black First Second Amount Amount Disper- MigrationParticles) Monomer Monomer Type (wt %) Type (wt %) sibility PropertiesExample 1B SC13MT 16k Siloxane KBE-503 n-butyl 1.0(3,3,3-TRIFLUOROPROPYL) 0.1 B 2 MA trimethoxysilane TRIMETHOXYSILANEExample 2B SC13MT 16k Siloxane KBE-503 n-butyl 1.0 0.3 A 3 MAtrimethoxysilane Example 3B SC13MT 16k Siloxane KBE-503 n-butyl 1.0 1.0A 4 MA trimethoxysilane Example 4B SC13MT 16k Siloxane KBE-503 n-butyl0.1 0.3 A 3 MA trimethoxysilane Example 5B SC13MT 16k Siloxane KBE-503hexamethyl 1.0 0.3 A 3 MA disilazane Example 6B SC13MT 16k SiloxaneKBE-503 hexamethyl 0.1 0.3 A 3 MA disilazane Comparative SC13MT 16kSiloxane KBE-503 — — 0.3 B 3 Example 1B MA Comparative SC13MT 16kSiloxane KBE-503 — — — — C 1 Example 2B MA

As is clear from Tables 1 and 2, in the electrophoresis dispersionliquid of each example, the electrophoretic particles exhibited superiordispersibility and migration characteristics in the electrophoresisdispersion liquid.

In contrast, in the electrophoresis dispersion liquid of eachComparative Example, the electrophoretic particles demonstrated resultsin which the dispersibility and the migration characteristics were notsuperior caused by omitting the connection of the second compound (andfurther, third compound) to the base particle.

6-2.

The display performance as outlined below were evaluated for theelectrophoresis dispersion liquids prepared in the above 5.

Evaluation of Display Performance

That is, the white reflectivity when white is displayed and the blackreflectivity when black is displayed were measured with theelectrophoresis dispersion liquids prepared in 5. Above were each pouredinto a transparent electrode cell with a thickness of 50 μm, and thecontrast was calculated therefrom.

The results thereof were evaluated based on the evaluation criteriashown below.

Evaluation Standards

A: Contrast of 25 or higher.

B: Contrast of 20 or more to less than 25.

C: Contrast of 15 or more to less than 20.

D: Contrast of 5 or more to less than 15.

E: The contrast is less than 5.

The evaluation results are shown in Table 3.

TABLE 3 Example Example Example Example Example Example ComparativeComparative 1A 2A 3A 4A 5A 6A Example 1A Example 2A Example 1B B A B C AC D D Example 2B A A B B A B D D Example 3B B C C C C C D D Example 4B CB C C B C D D Example 5B A A B B A B D D Example 6B C B C C B C D DComparative D D D D D D E D Example 1B Comparative D D D D D D D DExample 2B

As is apparent from Table 3, in the electrophoresis dispersion liquidswith the combination of the white particle of each example and the blackparticles of each example, the electrophoretic particles demonstratedsuperior contrast, that is, display performance without aggregationarising between the white particles and the black particles in theelectrophoresis dispersion liquid.

In contrast, in the electrophoretic dispersion with the combinationincluding the comparative example of at least one of the white particlesand the black particles, aggregation arose between the white particlesand the black particles caused by leaving out the connection of thesecond compound to the base particles, and, as a result, the resultsdemonstrated that the contrast, that is, display performance, wasdeteriorated.

The entire disclosure of Japanese Patent Application No. 2015-185320,filed Sep. 18, 2015 is expressly incorporated by reference herein.

What is claimed is:
 1. An electrophoretic particle, comprising: aparticle including a first functional group on a surface; and a firstcompound, a second compound, and a third compound bonded to theparticle, wherein the first compound is a block copolymer that includesa dispersion portion derived from a first monomer including a site thatcontributes to dispersibility in a dispersion medium, and a bondingportion derived from a second monomer including a second functionalgroup having reactivity with the first functional group, and isconnected to the particle by reacting the functional group and thesecond functional group in the bonding portion, the second compound hasa lower molecular weight than the first compound, includes a non-polargroup and the second functional group, and is connected to the particleby the second functional group reacting with the first functional group,and the third compound has a lower molecular weight than the firstcompound, includes a charging group and the second functional group, andis connected to the particle by the second functional group reactingwith the first functional group.
 2. The electrophoretic particleaccording to claim 1, wherein the second compound is a silane couplingagent that includes the non-polar group and the second functional group.3. The electrophoretic particle according to claim 1, wherein the secondcompound is a block copolymer that includes a non-polar portion derivedfrom a third monomer including the non-polar group, and the bondingportion derived from the second monomer including the second functionalgroup.
 4. The electrophoretic particle according to claim 1, wherein thenon-polar group is a hydrocarbon group.
 5. The electrophoretic particleaccording to claim 1, wherein the molecular weight of the secondcompound is 100 or more to 1,000 or less.
 6. The electrophoreticparticle according to claim 1, wherein the third compound is a silanecoupling agent that includes the charging group and the secondfunctional group.
 7. The electrophoretic particle according to claim 1,wherein the third compound is a block copolymer that includes a chargingportion derived from the third monomer including the charging group, andthe bonding portion derived from the second monomer including the secondfunctional group.
 8. The electrophoretic particle according to claim 1,wherein the charging group includes at least one of a polarization groupand an ionic group.
 9. The electrophoretic particle according to claim1, wherein the molecular weight of the third compound is 100 or more to1,000 or less.
 10. The electrophoretic particle according to claim 1,wherein, in the first compound, the bonding portion is formed by 1 ormore to 10 or less units derived from the second monomer.
 11. Theelectrophoretic particle according to claim 1, wherein, in the firstcompound, the first monomer is a silicone macromonomer represented bythe following general formula (I).

[in the formula, R¹ is a hydrogen atom or a methyl group, R² is ahydrogen atom or an alkyl group having 1 to 4 carbon atoms, R³ is astructure including one type from an alkyl group having 1 to 6 carbonatoms and an ether group of ethylene oxide or propylene oxide, and n isan integer of 0 or more]
 12. The electrophoretic particle according toclaim 1, wherein the weight average molecular weight of the dispersionportion is 10,000 or more to 100,000 or less.
 13. The electrophoreticparticle according to claim 1, wherein, when the weight averagemolecular weight of the dispersion portion is A and the molecular weightof the second compound is B, A/B is 10 or more to 1,000 or less.
 14. Amethod of manufacturing an electrophoretic particle according to claim1, the method comprising: connecting the third compound to the particleby reacting the first functional group included in the surface of theparticle and the second functional group included in the third compound;connecting the first compound to the particle at the bonding portion byreacting the first functional group included in the surface of theparticle and the second functional group included in the first compound;and connecting the second compound to the particle by reacting the firstfunctional group included in the surface of the particle and the secondfunctional group included in the second compound.
 15. A method ofmanufacturing an electrophoretic particle according to claim 2, themethod comprising: connecting the third compound to the particle at thebonding portion by reacting the first functional group included in thesurface of the particle and the second functional group included in thethird compound; connecting the first compound to the particle at thebonding portion by reacting the first functional group included in thesurface of the particle and the second functional group included in thefirst compound; and connecting the second compound to the particle byreacting the first functional group included in the surface of theparticle and the second functional group included in the secondcompound.
 16. An electrophoresis dispersion liquid, comprising: theelectrophoretic particles according to claim 1; and a dispersion medium.17. The electrophoresis dispersion liquid according to claim 16, whereinthe dispersion medium is silicone oil.
 18. An electrophoresis sheet,comprising: a substrate; and a structure that is provided on thesubstrate, and that accommodates the electrophoresis dispersion liquidaccording to claim
 16. 19. An electrophoresis device, comprising: theelectrophoresis sheet according to claim
 18. 20. An electronic apparatuscomprising: the electrophoresis device according to claim 19.